BOOK OF ABSTRACTS
14th Australiasian Fluid Mechanics Conference
Adelaide University, South Australia December 9-14, 2001
Published by: Causal Productions Pty Ltd www.causal.on.net [email protected]
Page Session Name 2 PL Plenary Lectures 2 TR Topical Reviews 3 AA Aero-Acoustics 4 AD Aerodynamics 5 AR Atmospheric Research 6 BL Boundary Layers 8 CO Combustion 9 CF Computational Fluid Dynamics 13 OT Diverse Fluid Mechanics Topics 15 ET Experimental Techniques 17 GD Gas Dynamics 17 GW Groundwater 17 HL Hydraulics 18 HD Hydrodynamics 20 IF Industrial Flows 21 JW Jets and Wakes 25 MF Multiphase Flow 26 NN Non-Newtonian Flows 27 OG Oceanography 27 PF Pipe Flow 28 WE Wind Engineering
1 Plenary Lectures by the interaction of the laminar wakes with the leading edge. Re- gions of elevated background unsteadiness appear on either side The Fluid Mechanics of Natural Ventilation of the peak layer thickness, which share many of the characteristics Paul F. Linden of Klebanoff modes, observed at elevated Free Stream Turbulence Page: 1-8, Paper no. 1001 (FST) levels. However, for the low background disturbance level Abstract: Ventilation of buildings is a topic close to our experience, of the free stream (u /U1 < 0.05%), the layer remains laminar to but knowledge and understanding of the airflow within a building the end of the test section (Rx ≈ 1.4x106) and there is no evi- is usually scanty. Even in buildings with purpose built mechanical dence of bursting or other phenomena associated with breakdown ventilation or air conditioned systems, designers use crude rules to to turbulence. A vibrating ribbon apparatus is used to demonstrate specify the ventilation, and the result is often unsatisfactory. I will that the deformation of the mean flow is responsible for substan- review current understanding and research on ventilation concen- tial phase and amplitude distortion of Tollmien-Schlichting (TS) trating on the details of the air flow. I will establish some general waves. Pseudo-flow visualization of hot-wire data shows that the principles, such as why layered stratification occurs in steady flows breakdown of the distorted waves is more complex and occurs at and why some flows are intrinsically unsteady. a lower Reynolds number than the breakdown of the K-type sec- ondary instability observed when the FSN is not present. New Developments in Large Eddy Simulation of Complex Flows Topical Reviews P. Moin Page: 9-13, Paper no. 1002 Stability of Nonparallel Flows: ’Minimal Composite’ Theories Abstract: Recent developments in large eddy simulation method- Roddam Narasimha, Rama Govindarajan ology are reviewed. This includes advances in filtering for inho- Page: 33-40, Paper no. 2001 mogeneous flows, subgrid scale and wall modeling and numerical methods. In particular, a numerical method designed for unstruc- Abstract: The theory of linear stability of shear flows has been tured grids with arbitrary elements which is being used for com- studied extensively over much of the last century. Most stud- putations in the combustor of a gas turbine jet engine is described. ies have been based on the Orr-Sommerfeld equation for parallel Progress in LES of turbulent combustion at CTR is reviewed. flows, but in recent decades there have been several attempts at more general theories, including the use of parabolized stability Near-Wall Coherent Structure Generation in a Tur- equations. As shear flows tend in general to be nonparallel, the bulent Boundary Layer question has remained about the formulation of a proper theory Wade Schoppa, Fazle Hussain accounting for flow nonparallelism. Introducing the concept of Page: 15-21, Paper no. 1003 minimal composite equations, with the use of similarity coordi- Abstract: We present new insight into the generation of stream- nates, it has been possible during the last ten years to develop a wise vortices near the wall, and an associated drag reduction strat- hierarchy of stability equations ranging from an ordinary differ- egy. Growth of x-dependent spanwise velocity disturbances w(x) ential equation like the Orr-Sommerfeld (but not identical to it) to is shown to occur via two mechanisms: (i) linear transient growth, partial differential equations like the PSE. The approach through which dominates early-time evolution, and (ii) linear normal-mode minimal composite equations has now been extended to include instability, dominant asymptotically at late time (for frozen base effects of wing sweep and compressibility, and we present a re- flow streaks). Approximately 25% of streaks extracted from near- view of these developments and their implications. wall turbulence are shown to be strong enough for linear insta- ’Homogeneous Turbulence’ and its Relation to Real- bility (above a critical vortex line lift angle). However, due to vis- ω izable Flows cous cross-diffusion of streak normal vorticity y , normal mode W.K. George, H. Wang, C. Wollblad, T.G. Johansson growth ceases after a factor of two energy growth. In contrast, the Page: 41-48, Paper no. 2002 linear transient disturbance produces a 20-fold amplification, due to its rapid, early-time growth before significant viscous streak de- Abstract: This paper examines in some detail how the decay of cay. Thus, linear transient growth of w(x) is revealed as a new, ap- homogeneous turbulence in the absence of shear is affected by parently dominant, generation mechanism of x-dependent turbu- the constraints of finite boundaries. It demonstrates how the ra- lent energy near the wall. Combined transient growth/instability tio of the wavenumbers of the spectral peak to the lowest resolved of lifted, vortex-free low-speed streaks (above the instability cutoff wavenumber (or tunnel size to integral scale) can influence directly of streak strength) is shown to generate new streamwise vortices, the time dependence of the energy, the integral scale, and even the which dominate near-wall turbulence phenomena. Significantly, rate of decay of the turbulence. If this ratio is not large enough, the 3D features of the (instantaneous) vortices generated by tran- the length scales grow too slowly and the energy decays too fast. sient/instability growth agree well with the coherent structures Criteria are proposed for assessing the validity of the data; but few educed (i.e. ensemble-averaged) from fully turbulent flow, suggest- experiments or simulations satisfy them. ing the prevalence of this mechanism. Results suggest promising Challenges for Innovation in Aerodynamics new strategies for drag and heat transfer control, involving large- A.J. Smits scale (hence more durable) actuators, without requiring wall sen- Page: 49-56, Paper no. 2003 sors or control logic. Abstract: New challenges for innovation in aerodynamics are pre- Laboratory and Computer Experiments on Turbu- sented in the context of transonic, supersonic and hypersonic flight, lent Mixing as currently under consideration in the U.S. Paul E. Dimotakis Page: 23-24, Paper no. 1004 Some Basic Problems of Microfluidics P. Tabeling Abstract: This discussion covers some progress in turbulent mix- Page: 57-62, Paper no. 2004 ing stemming from experimental, modeling, and direct-numerical simulation (DNS) studies. Topics include the mixing transition, Abstract: I present here several phenomena, which (I believe) are results from DNS studies of the Rayleigh-Taylor instability in mis- worth being discussed, because of their practical importance, the cible fluids, experimental investigations in transverse jets and the scientific challenge they convey, or both. The phenomena I discuss assumption of isotropy in turbulence and mixing, and experiments here are : slip of simple liquids over smooth surfaces, gas flows in high-speed shear layers that elucidate some effects of compress- in microchannels, chaotic micromixing, two phase flows in mi- ibility on the mixed-fluid field. crochannels, microelectrohydrodynamics, and bottleneck effect. The descriptions are made in a pedagogical rather than technical Effects of Free-Stream Nonuniformity on Boundary style. The few topics presented here represent a number of mi- Layer Transition crofluidics situations of importance, which raise interesting fun- J.H. Watmuff damental and practical issues. Page: 25-32, Paper no. 1005 Abstract: Experiments are described in which fine wires are posi- tioned upstream of the leading edge of a flat plate to generate well- defined FSN (Free Stream Nonuniformity). Large spanwise thick- ness variations in the downstream boundary layer are generated
2 A Few Examples of Industrial Problems that would Experiments on Natural Convection Boundary Lay- Benefit from Improved Understanding of Fluid Flow ers -the Role of Instabilities Peter Mullinger John C. Patterson Page: 63-69, Paper no. 2005 Page: 87-94, Paper no. 2009 Abstract: Fluid flow plays an enormous, and underrated, role in in- Abstract: In this paper, an experimental investigation of the tran- dustrial processes and its contribution of is become more widely sient behaviour of the flow adjacent to a suddenly heated vertical recognised. Topics such as flow in ducts, air distribution between wall is described. The experiments confirm that the primary devia- burners, conveying of powders, mixing of fluids and powders, etc tion from one dimensional to two dimensional flow at a particular are becoming increasingly recognised as fluid flow problems. Many location occurs at the time at which the fastest traveling wave aris- of these problems are not well understood, yet the cost of failure ing from the perturbation caused at startup reaches that location. caused by incorrect design is very high. The author selects and Further, a secondary instability is identified which simultaneously describes a few industrial problems as examples where poor un- occurs along the full length of the boundary layer and, in some derstanding of the fluid mechanical issues leads to poor or un- locations along the plate, evidently triggers a deviation ahead of predictable performance and increased costs. Some of industry’s the arrival of the fastest travelling wave. needs could be met by better education, that is more effective ap- plication of existing knowledge, however achieving a better under- Aero-Acoustics standing of even a few of the more complex problems will not be Surface Pressure Measurements on a Group of Ide- easy and offers an exciting challenge to researchers. However the alised Road Vehicle Models potential benefits from a better understanding of the issues are F. Alam, G. Zimmer, Simon Watkins very significant and will often be applicable across a wide range of Page: 95-98, Paper no. 3, Paper Code: AA01 industries. Progress Made in Viscoelastic Fluid Mechanics Abstract: Aerodynamically generated noise in the A-pillar region D.V. Boger of a passenger vehicle can make a significant contribution to inte- rior noise and adversely affect passenger comfort. Many modern Page: 71-71, Paper no. 2006 vehicles still have high fluctuating exterior pressures due to flow Abstract: Many presentations have been made on the development separations in this region. A series of experimental investigations and the impact of constant viscosity elastic liquids and on the were performed to study the effects of the A-pillar and windshield progress made in predicting the influence of elasticity in complex geometry on the local flow and its potential for noise generation flows of viscoelastic fluids. The first major presentation in this using a group of idealized road vehicle models. Surface mean and area to an Australasian fluid mechanics conference was a keynote fluctuating pressures were measured on the side window in the A- address presented at the 9th Australasian Fluid Mechanics Con- pillar region at different Reynolds numbers and yaw angles. Tests ference held in 1986 in Auckland [2]. A similar presentation was were carried out in RMIT Wind-Tunnel. Flow structure was docu- made at the 10th Australasian Fluid Mechanics Conference held in mented using flow visualization. The studies show that Reynolds Melbourne in 1989 [1]. Here I am again, this time trying to bring number sensitivities were minimal and the surface mean and fluc- you up-to-date on what has happened in viscoelastic fluid mechan- tuating pressures can be scaled with velocity head and Strouhal ics. number if no feedback mechanism is present. The magnitudes There are two recent papers to which you might refer if there is of the fluctuating pressure coefficients depend largely on local A- interest in this topic. The first, in Theoretical and Applied Me- pillar radii and can be reduced significantly with the increase of chanics in 1996 [8], looked at Newtonian elastic liquids and exam- local corner radii. ined the effectiveness of predicting the influence of elasticity in Computation of Acoustic Waves Generated by a Co- slow (creeping) flows for constant viscosity elastic fluids. The flow Rotating Vortex Pair fields examined included exit flow from a capillary tube and creep- K. Liow, M.C. Thompson, K. Hourigan ing flow around a sphere. A flow field not examined in that article Page: 99-102, Paper no. 139, Paper Code: AA02 was tubular entry flows [3], a topic of great interest in the numeri- Abstract: The far field acoustic effects of a co-rotating vortex pair cal simulation community worldwide. The latest paper, published are modeled using Lighthill’s [4] theory of turbulence-generated in Applied Rheology [7], examines the properties of low viscos- sound and Powell’s [9] theory of vortex sound. To do this, the flow ity elastic liquids. The flow fields examined with these water-like and acoustic fields are decoupled. The unsteady incompressible elastic liquids include jet breakup, drop impact and swirling flows viscous flow field is modeled using conventional computational [9,10]. Swirling flow work is of particular interest because the in- fluid dynamics techniques. The sound field is modeled separately teraction between inertia and elasticity in a relatively simple flow is using an inhomogeneous wave equation where the source is com- examined. This presentation will use many photographs from Rhe- puted from the flow field variables. The robustness of the com- ological Phenomena in Focus [4] to illustrate how important fluid putational method in implementing Lighthill’s [4] and Powells’s [9] elasticity can be in complex flows. theories is demonstrated. The results are compared with those The latest work in drop formation, drop impact and the interaction from direct numerical simulation (DNS) [7] and the analytical solu- between surfactants and polymers in viscoelastic fluids will also be tion of [8]. It is found that by choosing an appropriate initial condi- discussed [5,6]. This latter work is of direct interest in the deliv- tion to the aeroacoustic governing equation, the levels of spurious ery of agricultural chemicals and in inkjet printing. A complete waves are reduced quite dramatically. manuscript has not been written as everything to be presented is published elsewhere. An Instance of Cavity Resonance Interaction with an Open-Jet Tunnel Free Shear Layer Environmental Exchange Flows J. Milbank, Simon Watkins, R.M. Kelso G.N. Ivey Page: 103-106, Paper no. 155, Paper Code: AA03 Page: 73-78, Paper no. 2007 Abstract: Using an aeroacoustic open-jet open-circuit tunnel a study Abstract: Exchange flows refers to the transport between fluid into feedback resonance at small cavity scale and low subsonic flow reservoirs with differing fluid properties. The issue of importance speeds was undertaken. During the preliminary tests the cavity is the prediction of the rate of exchange and the study of this prob- resonance appeared to be affected by another mechanism, and was lem both historically and dynamically can be thought of as a pro- not a pure feedback resonance. The resonance peaks were broad, gression from hydraulics to mixing. This progression is reviewed frequency shifted, with many secondary peaks existing on the main in this work. peak. An investigation was performed to determine whether the Wind Wave Evolution in Finite Depth Water alignment of the model containing the cavity, or its proximity to I.R. Young, A.V. Babanin the test facility free shear layer, were the cause of the unusual res- Page: 79-86, Paper no. 2008 onance characteristics. The results seem to show that the model alignment makes the resonance more or less susceptible to inter- Abstract: This paper presents recent research aimed at developing action with other mechanisms, but proximity to the test facility a detailed predictive capability for wind generated ocean waves in free shear layer is, in this case, the cause of the observed charac- shallow coastal waters. The detailed evolution of the directional teristics. spectrum, and measurements of the source terms responsible for this evolution are presented.
3 Simulation of Acoustic Resonance Generated by The Dependence of the Discharge Coefficient on Flow Around a Long Rectangular Plate Placed in a Density Contrast - Experimental Measurements Duct Joanne M. Holford, Gary R. Hunt B.T. Tan, M.C. Thompson, K. Hourigan Page: 123-126, Paper no. 93, Paper Code: AD02 Page: 107-110, Paper no. 237, Paper Code: AA04 Abstract: The discharge coefficient Cd associated with a strongly Abstract: This paper describes a numerical investigation of acous- contracting flow through a sharp-edged orifice is, in general, as- tic resonance occurring at specific flow speeds when a long rect- sumed to be constant at sufficiently high Reynolds numbers. The angular plate is placed in a duct. To do this, the flow and acoustic effect of buoyancy forces due to a difference in density between problems are decoupled. This allows the range of flow speeds, the fluids on either side of the opening is typically ignored. In the or the associated Strouhal number (Stc ), where resonance is pos- absence of a buoyancy contrast, the discharging flow contracts due sible to be predicted. It is shown that the Strouhal number dis- to inertial effects giving Cd ≈ 0.6. We hypothesise that a density plays a stepping behaviour as the plate length is increased. The contrast may cause a significant reduction in Cd for flows through main source or sink region where energy to transferred between horizontally or vertically orientated openings. We test this hypoth- the acoustic and flow fields is shown to be just downstream of the esis by deducing Cd from laboratory measurement of the volume trailing edge of the plate. Visualizations show that the timing when flow rate driven through an opening by hydrostatic pressure dif- the vortices enter this region relative to the phase of the acoustic ferences in a two-layer saline stratification in water. cycle is crucial in determining if resonance can occur and is the Plume theory shows that a discharge of buoyant fluid from an area cause of the observed stepwise increase. source may contract in addition to the inertial contraction. The dis- The Contribution of the A-Pillar Vortex to Passenger charge through a horizontal or vertical opening is characterised by Car In-Cabin Noise conditions at the opening, represented by the dimensionless dis- G. Zimmer, F. Alam, Simon Watkins charge parameter Γd, which is a function of the volume, buoyancy Page: 111-114, Paper no. 271, Paper Code: AA05 and momentum fluxes at the opening. For horizontal openings, once a critical value of Γd is exceeded, Cd exhibits a strong de- Abstract: The flow around the A-pillar of a passenger car is a pendence on the density contrast and decreases rapidly with in- source of aerodynamic noise as well as a source of surface pressure creasing Γd. For vertical openings, Cd decreases with Γd, for all fluctuations on the side window glass. A car was fitted with flush Γd. The dependence of Cd on density contrast implies a potential mounted microphones to measure surface pressure fluctuations for serious errors in the prediction of volume flow rates through and an Aachen Head system to measure interior noise. Testing constrictions if a constant value of Cd is assumed, as is current was carried out in two different wind tunnels, as well as on road. practice. Testing was carried out with the vehicle in factory trim, and also with the addition of acoustic insulation to reduce mechanical, tyre, Mean Velocity, Reynolds Stress and Static Pressure and aerodynamic noise other than from the A-pillar region. It was Measurements in an Air Cyclone found that simple changes in geometry have significant effects on J.D. Hooper, Simon Watkins reducing flow separation in this area, however the difference in in- Page: 127-129, Paper no. 95, Paper Code: AD03 terior noise SPL in realistic on-road driving conditions is not readily Abstract: The flow field in a gas cyclone with no particulate load discernable. was documented using a dynamic Cobra pressure probe. The six Aerodynamics Reynolds stresses as well as the time-averaged velocity vectors were mapped for nine stations. A relatively low turbulence level Interference Drag Between Spherical and Cylindri- vortical flow was found in the outer regions of the cyclone body cal Particles in Stokes Flow but high turbulence levels were measured below the vortex finder, A.K.W. Cheung, B.T. Tan, K. Hourigan, M.C. Thompson although here the mean tangential velocity distribution was well Page: 115-118, Paper no. 35, Paper Code: AD01 defined as solid body rotation. The time-averaged results were in Abstract: In this study, predictions are made for the interference fair agreement with a numerical study and further work is planned effects when two cylinders or two spheres are placed in series or with a low particulate load in the flow. parallel in a low Reynolds number flow. Using a spectral element Some Aspects of the Aerodynamics of Membrane method, it is predicted that for two cylinders with their line of Wings centres perpendicular to the flow, the drag force is lower than the Peter S. Jackson, Michael S. Johnston, Richard G. J. Flay isolated cylinder case at small gaps but is greater at all other gaps; Page: 131-134, Paper no. 106, Paper Code: AD04 a maximum is found at a gap of approximately of 7 cylinder di- ameters. The result is fundamentally different to the case of two Abstract: The primary aim of this paper is to explore some of spheres with their line of centres perpendicular to the flow, which the consequences of membrane stiffness for real flying membrane has an analytical value reported in Happel and Brenner [7]; in that wings, with emphasis on the structural stiffness due to the initial case the drag force on each sphere is less than an isolated sphere shape as well as the elasticity of the membrane itself. Earlier work at all gaps. For cylinders with their lines of centres parallel to the has concentrated on the effect of membrane stretch on lift, but flow, the drag on the trailing body is less than the leading body, since this analysis is set in the context of a flying wing supporting which in turn is less than the drag on an isolated cylinder. In the an aircraft or animal the effect of membrane stiffness on the pitch- case of spheres, the drag on the individual bodies is similar and ing moment is also presented. The constraint of fixed lift force is less than the drag on an isolated body for all gaps. However, in then shown to make significant changes to the apparent effect of the case of cylinders, the drag on the leading body is significantly membrane deformation. The paper develops the work of Johnston greater than that on the trailing cylinder. [6], who investigated the gliding flight of the dinosaur Pteranodon ingens. Physical Mechanism of Incipient Separation in Shock Wave / Boundary Layer Interactions Induced Research and Testing in the New Transonic Wind by a Sharp Fin Tunnel at AMRL Hua-Shu Dou, Nhan Phan-Thien N. Matheson, S.S. Lam Page: 135-138, Paper no. 146, Paper Code: AD05 Page: 119-122, Paper no. 64 Abstract: In this paper, the incipient separation induced by shock Abstract: Details of the new Transonic Wind Tunnel constructed wave/turbulent boundary layer interactions at sharp fin is pre- recently at the Aeronautical and Maritime Research Laboratory (A- dicted with Dou and Deng’s theory, and is compared with Lu and MRL) are given in this paper. The tunnel was completed and handed Settles’ experimental data. The physical mechanism of the incip- over to AMRL in March 2000. Since that time, the tunnel has been ient separation induced by shock wave/turbulent boundary layer used on a variety of projects to meet Defence needs. Details of interactions at sharp fin is explained through the surface flow pat- some of the tests carried out to date are given, together with brief tern analysis. The reason for the discrepancy in the predicted and details of future research that is currently being planned. experimental incipient separation conditions is clarified. In addi- tion, a correlation for the correction of incipient separation angle predicted by theory is also given.
4 Görtler Vortices in Curved Mixing Layers and Their The Aerodynamic Characteristics of a Family of Fly- Effect on the Inherent Instabilities ing Wing Shapes Suited for Small RPVs S.R. Otto, T.R. Cole Simon Watkins Page: 139-142, Paper no. 173, Paper Code: AD06 Page: 155-158, Paper no. 253, Paper Code: AD10 Abstract: Curved mixing layers are known to be inherently unsta- Abstract: For aircraft such as small rpv’s, simple, yet light and ro- ble to short wavelength traveling waves (due to the layer’s inflec- bust flying surfaces can now be constructed using post-buckled tional nature) and longitudinal vortex structures (due to the change carbon fibre struts that are covered with a thin sheet of stretched in circulation); these are akin to Görtler vortices. We shall discuss plastic film. The longitudinal aerodynamics characteristics of a the latter through their linear evolution and subsequent nonlinear class of shapes resulting from various degrees of buckling are ex- growth. Depending on the size of the instability and other pa- amined by a series of wind-tunnel tests under the same scale and rameters this may cause the flow to breakdown. This manifests flying speeds typical of such rpv’s. Lift curve slopes and lift/drag itself as large jets in the neighbourhood of the centre line of the polars are presented that shown the different characteristics. The mixing layer. Prior to the actual breakdown, the flow becomes in- maximum lift/drag ratios are similar for all the (quite different) flectional in the spanwise coordinate and has additional structure shapes but the stall characteristics are markedly different. in the normal direction. One is compelled to solve the Rayleigh How Accurately is a Helical Vortex Represented by stability equation with variation in the underlying state in more Straight Segments? than one variable; this requires a sophisticated numerical method D.H. Wood, D. Li to solve the resulting partial differential eigenvalue problem. The Page: 159-162, Paper no. 258, Paper Code: AD11 presence of the vortices and their effect on the intrinsic travelling waves are discussed, with a view to using their existence to control Abstract: This paper assesses the accuracy of representing a heli- these waves. cal vortex, as found in the wakes of helicopters, wind turbines, and PIV Measurements in a Forced Separated Shear propellers, as a sequence of straight segments. For the first time, Layer from a Blunt Leading Edge comparison is made with recent results for the induced velocity of N.R. Panchapakesan, J. Soria a helix of constant pitch and radius. Three cases are considered. The first, the velocity on the helix axis, has an analytic solution that Page: 143-146, Paper no. 175, Paper Code: AD07 is used to demonstrate the second order accuracy of the approxi- Abstract: We report results from an experimental investigation of mation. The second case, representing a second vortex at the same the separated flow from a square blunt leading edge. Earlier flow radius, shows the segments in line with the control point dominate visualization studies have indicated that forcing a shear layer such the error. Thirdly, the self-induced velocity is determined to within as this with amplitude ratios of the order of 0.3 referred to the free an accuracy comparable with the effects of the vortex structure, of stream velocity significantly modifies the flow structure in the sep- which little is presently known. arated region. The present study characterizes the effects of these high amplitude ratios and the excitation frequency using particle Frequency and Amplitude Effects in the Wake of a image velocimetry. The study was conducted in a water tunnel of Plunging Airfoil section size 500 mm by 500 mm with a blunt leading edge model of J. Young, J.C.S. Lai 25 mm thickness at a Reynolds number of about 1000. The forcing Page: 163-166, Paper no. 265, Paper Code: AD12 flow was imposed through a slit of 0.5 mm width located close to Abstract: The flow over a 2D airfoil, oscillated sinusoidally in plunge, the separation corner. The results indicate that higher amplitudes is simulated using a compressible Navier Stokes solver at Reynolds produce additional coherent structures in the shear layer which number 30,000. Close agreement is obtained between numerically modify the interaction between the free stream and the separated simulated wake structures and experimental wake visualisations flow region. in the literature. Thrust of the airfoil and detailed wake structures Impulsively Started Flow over an Airfoil at an Angle are shown to be strongly dependent on both the Strouhal num- of Attack ber and the reduced frequency of the plunge oscillation, at this K. Parker, J. Soria, T.T. Lim, T.H. New Reynolds number. The findings are postulated to be the result of a vortex shedding frequency lock-in phenomenon, similar to that Page: 147-150, Paper no. 177, Paper Code: AD08 observed for transversely vibrating circular cylinders. Abstract: This paper reports on a preliminary study undertaken to investigate the evolution and structure of ow accelerated from Re Dependence of the Energy Dissipation Rate and a stationary state over a NACA 0015 airfoil at an angle of attack Spectrum in Shear Flows of 30◦. The results from two uniform accelerations of 50 mm/s2 B.R. Pearson, P.-Å. Krogstad, M.A. Carper and 100 mm/s2 are presented. In both cases the final uniform Page: 167-170, Paper no. 276, Paper Code: AD13 velocity was 100 mm/s. The Reynolds number based on this uni- Abstract: The 1-dimensional surrogate for the dimensionless mean form velocity and the chord length of the airfoil was 8000. PIV energy dissipation rate Cε is measured in shear flows over a range measurements were conducted to measure the in-plane velocity of the Taylor micro-scale Reynolds number Rλ range 70 Rλ field and the out-of-plane vorticity evolution around the airfoil. 1217 When Cε is defined with respect to a length scale derived These measurements have revealed a rich and complex unsteady from the energy spectrum, a value of Cε ≈ 0.5, when Rλ 300 ap- flow structure. The observable dispersion of vorticity seen in both pears to be a good approximation in regions free of strong mean acceleration cases is indicative of the unsteady 3-D nature of the shear. Both large- and small-scale normalized forms for the 1- flow. The results show that the evolution of the dynamic stall vor- dimensional energy spectrum φu(k1) are used to unambiguously tex is retarded in the faster acceleration case. identify the spectral scaling range. The scaling range power-law ex- Visualization of a Three Dimensional Heaving Aero- ponent and the spectral Kolmogorov constant are estimated and foil Flow their dependence on Rλ is demonstrated. K.D. von Ellenrieder, K. Parker, J. Soria Page: 151-154, Paper no. 249, Paper Code: AD09 Atmospheric Research Abstract: The structure of the flow behind a three dimensional Particle-Pair Separation Processes in Turbulence aerofoil, which performs pure heaving oscillations, is examined M.S. Borgas, P.K. Yeung for a flow Reynolds number of 164, and heaving Strouhal numbers Page: 171-174, Paper no. 14, Paper Code: AR01 between 0.2 and 0.4. Dye flow visualization is used to study the Abstract: The role of viscous effects during the Lagrangian separa- flow from the front, side and rear of the aerofoil. A comparison tion process for pairs of fluid particles moving apart in turbulent with the flow around an infinite-span aerofoil with the same thick- flow is highlighted. New models based on the important physics ness and chord, and which operates at the same Reynolds number are compared with direct numerical simulations. Rare but extreme and Strouhal numbers, reveals that the three dimensional and two flow events (large strains) are identified and are shown to critically dimensional heaving aerofoil flows are substantially different. The constrain the model separation performance. Adequate account structures in a two dimensional foil flow are predominantly orien- of the extremes is essential for good models, but has not been tated along the spanwise direction. In contrast, v-shaped vortex adopted previously in the literature. structures, which are partially aligned with the aerofoil wingtips, are formed in a finite-span aerofoil flow.
5 Project Prairie Grass - a Classic Atmospheric Disper- tance downstream from the leading edge of the plate. In order to sion Experiment Revisited quantify separation for a non-Newtonian fluid, the boundary-layer B.L. Sawford equations, in both similar and non-similar form, are solved. Our Page: 175-178, Paper no. 206, Paper Code: AR02 results demonstrate that shear-thinning fluids can act as a useful Abstract: We revisit the data from Project Prairie Grass to ex- deterrent of flow separation. plore some fundamental aspects of vertical dispersion in the at- Structure of Rough Wall Turbulent Boundary Layers mospheric surface layer using modern stochastic theories of tur- at Relatively High Reynolds Number bulent dispersion. In particular, we examine the relationship be- S. Bisceglia, R.J. Smalley, L. Djenidi, R.A. Antonia tween the diffusion equation (K-theory) and first-order Lagrangian Page: 195-198, Paper no. 61, Paper Code: BL06 stochastic models (Langevin models) over a range of stabilities. We also attempt to resolve some conflicting earlier studies that imply Abstract: The effect of two different types of surface roughness on significantly different values for the von Karman constant for the a turbulent boundary layer was studied using 2-component LDV transfer of matter, or equivalently of the turbulent Schmidt num- measurements in a relatively high speed water tunnel. One rough- ber. Finally, we assess the importance of surface deposition in the ness consists of square bars at a stream-wise spacing p equal to 2k Project Prairie Grass data. (k is the roughness height). The other consists of cylindrical rods with p/k equal to 4. Both roughnesses are aligned in a direction Boundary Layers transverse to the flow. Measurements of the turbulent field were carried out over a wide range of Reynolds numbers, (1500 < Rθ Symmetry Breaking to Modulated Rotating Waves in < 23000) based on the momentum thickness. Comparison of the an Enclosed Swirling Flow turbulent field between different surfaces is made at Rθ ∼ 9000. H.M. Blackburn, J.M. Lopez This study supports previous attempts to classify rough surfaces Page: 179-182, Paper no. 11, Paper Code: BL01 according to their turbulence characteristics, and extends them by Abstract: Rotating waves are a generic instability mode of flows providing measurements at high Reynolds numbers for three dis- that possess a rotation symmetry, such as Taylor-Couette flow. In tinct surface conditions. the enclosed swirling flow that is generated in a closed cylindri- The Effect of Diffusive Mass Transfer on Boundary- cal container by a rotating end- wall, the initial bifurcation to un- Layer Stability steadiness produced by increasing the endwall rotation rate can be I.A. Halatchev, J.P. Denier either to rotating waves or unsteady axisymmetric flow, depending Page: 199-202, Paper no. 84, Paper Code: BL07 on the aspect ratio of the cylinder. We examine a case where the initial bifurcation is to a periodic axisymmetric state, and follow Abstract: We consider the linear stability of a boundary-layer flow subsequent bifurcations to other states where the flow breaks ax- over a permeable .at plate under conditions of intense interfacial isymmetry as well. These resulting states possess rotating waves mass transfer. The stability of the flow is governed by an Orr- that are modulated by the underlying axisymmetric behaviour. Al- Sommerfeld type equation coupled to a second-order differential though this flow also has axial vortex breakdowns, they appear to equation for the concentration disturbance field through a flux play no dynamical role in the symmetry breaking, remaining es- boundary condition at the permeable surface. This is solved to sentially axisymmetric. determine the regions of parameter space in which the flow is lin- early unstable. In particular, the critical Reynolds number for the Pressure Field Calculation in Flow Simulation by Dis- flow is obtained. crete Vortex Method Turbulent Boundary Layer Evolution Towards Equi- K.L. Lai, M.K. Bull librium Conditions Page: 183-186, Paper no. 23, Paper Code: BL03 A.K. Hellstedt, M.B. Jones, M.S. Chong Abstract: In numerical simulations of fluid flow by discrete-vortex Page: 203-206, Paper no. 88, Paper Code: BL08 methods, the natural processes of vorticity creation at solid bound- Abstract: The outline for a closure hypothesis to enable the com- aries and vorticity evolution in the flow domain are directly mod- putation of the streamwise evolution of two-dimensional turbulent elled. The governing equations are formulated in terms of vortic- boundary layers in arbitrary pressure gradients is presented. Util- ity, with the pressure terms eliminated. The calculations then yield ising the Coles [1] logarithmic law of the wall and law of the wake directly the evolution of the vorticity field. From the vorticity field, formulation, in conjunction with the mean continuity and mean streamlines and pressure fields are readily obtainable. The deriva- momentum equations, the important non-dimensional parameters tion of the pressure field involves evaluation of the time-rate of which describe the state of a general non-equilibrium boundary change of the velocity potential resulting from variation with time layer are identified. These parameters form the basis of the clo- of the surface-vorticity on solid boundaries. The velocity potential, sure hypothesis, which is achieved empirically from experiments. and hence the pressure, can formally have physically-inadmissible The range of application of the proposed scheme is examined by multiple values. Numerical procedures for the derivation of the studying a zero-pressure-gradient flow leading to a sink flow. pressure field from the vorticity field are detailed, which prevent the occurrence of multiple values or discontinuities in the calcu- Interaction Between Turbulence Wedges which De- lated pressure. velop from Roughness Row in a Flat Plate Laminar Boundary Layer Turbulent Drag Reduction by Spanwise Wall Oscil- M. Ichimiya, C. Sudo lation Jung-Il Choi, Chun-Xiao Xu, Hyung Jin Sung Page: 207-210, Paper no. 104, Paper Code: BL09 Page: 187-190, Paper no. 37, Paper Code: BL04 Abstract: Experiments were performed to investigate the effect of a three- dimensional roughness row on boundary-layer tran- Abstract: Drag reduction in turbulent channel flows by spanwise sitions on a flat-plate with zero pressure gradient. Each rough- wall oscillations is studied numerically. A simple equation express- ness element was a cylinder 2 mm in both diameter and height. ing the drag reduction rate (Dr ) by spanwise oscillations as a pri- + Eleven elements formed a row in the spanwise direction. Wedge- mary function of the oscillating velocity (Vc ) is derived from the shaped turbulent regions ("turbulence wedges") developed down- interaction between the Stokes layer and near-wall turbulence. By stream from the respective roughnesses. Further downstream, two using this parameter, the drag reduction shows a good similarity + adjacent wedges merged together and then a two-dimensional tur- with Vc . The influence of the Stokes layer on the relation between bulent boundary layer was formed. Velocities were measured by near-wall streamwise vortices and low- and high-speed fluids is ex- hot-wire anemometers inside and outside the wedge regions, and amined to extract the key parameter. an intermittency factor and vorticities for streamwise vortices were Blowing-Induced Boundary-Layer Separation of obtained. Shear-Thinning Fluids When we compare the respective turbulence wedges from the pre- P.P. Dabrowski, J.P. Denier sent roughness row with a wedge developed from a single rough- Page: 191-194, Paper no. 54, Paper Code: BL05 ness element in a previous study, we find that (1) the wedge ex- Abstract: We consider the problem of blowing-induced boundary- pansion angle in the spanwise direction with the roughness row layer separation of a general class of shear-thinning fluids. A uni- was same as that with the single roughness; also wedge develop- form blowing velocity is prescribed at the surface of a .at plate. ments in the wall-normal direction for both cases were same, (2) In the case of a Newtonian fluid this flow separates at a finite dis- more streamwise vortices appeared within the present wedges, (3)
6 the scales of the streamwise vortices in the present wedges were using simultaneously measured values of filtered wall shear stress smaller, and (4) the mean vorticities in the present wedges were and filtered velocities in a turbulent boundary layer at Rθ = 3500. larger. The data was collected using arrays of hot-film wall shear stress × Experimental Study of High Reynolds Number Tur- sensors and -wire velocity probes. The models based on the bulent Boundary Layers - Mean Flow Scaling streamwise component velocity perform better than those which M.B. Jones, N. Nishizawa, M.S. Chong use the wall-normal component. A new model, also based on the streamwise component of velocity, is proposed that more accu- Page: 211-214, Paper no. 109, Paper Code: BL10 rately describes the shear stress measured at the wall. The new Abstract: Preliminary experimental results are presented for high model is expected to be more applicable over a larger range of Reynolds number turbulent boundary layers. A at plate zero pres- Reynolds number and wall normal positions within the logarith- sure gradient layer has been studied in a new high Reynolds num- mic region because it follows ’outer-flow’ scaling similarity. ber boundary layer tunnel. Measurements were made of the mean flow up to Reynolds numbers of 6.0 × 104 based on momentum Experimental Study of Turbulent Flow Along a thickness. The data supports the existence of a logarithmic law of Streamwise Edge (Chine) the wall in the overlap region and constants κ = 0.41 and A = 5.0 K.A.M. Moinuddin, S. Hafez, P.N. Joubert, M.S. Chong are found to best fit the data. Page: 231-234, Paper no. 157, Paper Code: BL15 Assessment of Local Blowing and Suction in a Tur- Abstract: An experimental study of the development of the turbu- bulent Boundary Layer lent boundary layers along a streamwise chine will be presented. Kyoungyoun Kim, Hyung Jin Sung This flow represents a special class of three-dimensional turbulent Page: 215-218, Paper no. 121, Paper Code: BL11 boundary layers, where secondary flow is induced by inequality of Reynolds stresses around the edge. The direct effect of this edge Abstract: Effects of local blowing or suction from a spanwise slot flow is to increase the drag force. A recent study along a right- on a turbulent boundary layer flow are investigated using the di- angled streamwise edge was given by Panchapakesan & Joubert rect numerical simulation technique. Three different blowing or (1988 and 1999). These measurements provided, in qualitative suction velocities are imposed on the slot keeping blowing or suc- terms, the general behaviour expected from this class of flow as re- tion flow rate constant. The recoveries of mean wall pressure for vealed by Elder (1960), but they suffered from asymmetry about the the different blowing velocities collapse well on the same recovery edge bisector due to overall flow geometry, especially side wall con- line. However, each wall pressure recovers just after the slot for tamination. The developing edge vortices were affected unevenly suction. In the blowing case, the relaxation of rms wall pressure by the growing corner vortices. By altering the effect of the tunnel fluctuations and pressure gradient after the slot is seen and the re- side walls, quasi-symmetry was achieved. Our measurements in- laxation distance from the slot center is nearly constant for three dicate symmetry about the bisector with a maximum deviation of different blowing velocities. In the suction case, the flow recovers 5 percent. Measurements were carried out on a 6 metres long test from the immediate rear of the slot. These features are also ob- model at a station 4.665 m from the trip wire. This downstream served in three-dimensional views of the near-wall vortices. station was chosen with an understanding that symmetry at this Flow Field Calculation in a Turbulent Lubrication station would likely ensure symmetry everywhere upstream. Film The Mean Velocity Profile for Wall-Bounded Flows P.B. Kosasih, A.K. Tieu at Low Reynolds Number Page: 219-222, Paper no. 126, Paper Code: BL12 T.B. Nickels Abstract: A simple computational technique to calculate the veloc- Page: 235-238, Paper no. 165, Paper Code: BL16 ity field in a laminar-turbulent hydrodynamic lubricant film is pre- Abstract: A useful form is proposed for the mean velocity profile sented. A modified eddy viscosity model to express the Reynolds in turbulent wall-bounded flows. This form is used to investigate stresses was used in the computation. There are two physical as- the effects of pressure-gradients on low Reynolds number flows. pects of lubricant flow to be considered in the model. Firstly, the flow in a lubrication film occurs in a very thin film, and as such un- Effect of Wall Suction on a Turbulent Boundary less the bearing’s Reynolds number is very large, a velocity profile Layer: Reynolds Number Dependence governed by the universal law of wall will not be established. The O. Oyewola, L. Djenidi, R.A. Antonia eddy viscosity model must be able to cover this region. Secondly, Page: 239-242, Paper no. 174, Paper Code: BL17 favourable and adverse pressure gradients are always present in Abstract: Single hot wire measurements have been made in a tur- the lubrication film. The effect of these pressure gradients is ac- bulent boundary layer subjected to localised wall suction, applied counted for in the model in the computational procedure. Using through a porous strip, at various Reynolds numbers and suction the technique, the effect of various typical hydrodynamic lubrica- rates. The measurements of the skin friction coefficient (with a tion flow conditions such as Reynolds numbers and pressure gra- Preston tube) not only confirm that pseudo-relaminarization can dients is presented for a long bearing case. occur immediately downstream of the strip, but they also show A Structure Detection Method Based on Wavelets that the Reynolds number/suction rate combination is the main J.H. Kaspersen, P.-Å. Krogstad factor controlling it. The mean and rms velocity profiles depart R σ R Page: 223-226, Paper no. 129, Paper Code: BL13 from the corresponding undisturbed profiles for all θ0 and ( θ0 is the Reynolds number based on the momentum thickness of the Abstract: A method to detect turbulent structures using Wavelets boundary layer in the absence of suction at the leading edge of the is presented. From the Wavelet spectrum the most energetic scale suction strip and σ is the suction rate), the departure being more is determined. The structures may then be detected according to pronounced at the largest σ and smallest Rθ . which quadrant this dominant scale signal falls within. The ad- 0 vantage of this method compared to previous methods is that it Artificial Thickening of Wind Tunnel Boundary Lay- does not need any threshold parameter or detection window. The ers via an Array of Cross-Flow Jets method is applied to the data from a rake of 8 x-wires taken in a J.L. Roberts, G.J. Walker turbulent boundary layer. It is shown that the correlations from Page: 243-246, Paper no. 198, Paper Code: BL18 this single scale contains most of the characteristics of the conven- Abstract: A novel method of artificially thickening the boundary tional two-point correlations which contain the added information layer for realistic waterjet propulsion intake studies in aeronautical from all scales. This therefore demonstrates that the method se- wind tunnels is described. An array of various sized jets in cross lects the most important flow events. Conditional averages resem- flow is shown to have the benefits of producing realistic momen- ble closely the results obtained from the well established Quadrant tum and turbulence profiles within a small streamwise distance of method. the jet array. Due to the operational static pressure of the wind- Experimental Study of Near-Wall Models for Large- tunnel being below ambient, the pressure differential required to Eddy Simulation operate the jets is supplied by the normal tunnel operation. The G.J. Kunkel, I. Marusic, F. Porté-Agel air supply to the jet array is easily throttled allowing for a variable Page: 227-230, Paper no. 131, Paper Code: BL14 amount of boundary layer thickening. This technique has been Abstract: Three conventional large-eddy Simulation (LES) bound- successfully applied to model the flow in flush-type intakes used ary conditions, based on the instantaneous filtered velocity at lo- by high-speed catamaran ferry vessels. cations nominally within the log region, are tested experimentally
7 On Open Venturis of the surface-pressure field. The investigation ranges over axial E.O. Tuck flow; flows with small angles of yaw (up to 1◦), which produce dis- Page: 247-250, Paper no. 243, Paper Code: BL19 torted but still-recognisable boundary layers; and flows at yaw an- ◦ Abstract: Flow through an open converging-diverging channel, aimed gles (up to 9 ) sufficiently large for the boundary-layer flow to give at achieving maximum velocity at the throat. way to oblique vortex shedding from the cylinder. It is concluded Interpretation of Space-time Velocity Correlations in that the spectra of axisymmetric boundary layers are consistent Wall Turbulence with the distinct frequency regimes which characterise the spec- A. K. Mesbah Uddin, I. Marusic, P.K. Subbareddy tra of planar boundary layers, but that the low-frequency regime may be more extensive; and that, despite the gross asymmetries in Page: 251-254, Paper no. 245, Paper Code: BL20 the outer regions of the boundary layer produced by small yaw an- Abstract: Two point space-time correlations of velocity fluctua- gles, the scale of the main pressure-producing region of the layer tions have long been viewed as containing a wealth of information changes very little with yaw angle. about the geometric and statistical structure of eddies in turbu- lent flows. In this paper, an attempt is made to interpret these Combustion measurements in light of Townsend’s attached eddy hypothesis. Both numerical (DNS) and experimental data are considered. The Combined PDA/LIF Measurements in Simple, Evap- experiments were carried out at two different Reynolds numbers orating Turbulent Spray Jets in order to interpret the Reynolds number effects in terms of eddy Yung-Cheng Chen, Sten H. Starner, Assaad R. Masri Page: 267-270, Paper no. 31, Paper Code: CO01 geometry. The DNS data set comes from the channel flow sim- ulation of Moser, Kim & Mansour[5]. A simulation based on the Abstract: This paper is part of a continuing study aimed at in- attached eddy hypothesis tests a conjecture for certain geometric vestigating the structure of non-reacting and reacting turbulent and dynamic properties of the constituent eddies, by comparing spray flows. A simple jet nozzle is used to produce a slender the statistics gathered from experiment and DNS. shear flow in a co-flowing air stream with well-defined initial and boundary conditions. The flow is made intentionally simple and The Structure of Longitudinal Vortices Within the relatively easy to model so that the focus can be on the important Atmosphere aspects of droplet evaporation rates and turbulence- droplet in- C.E. Watson, S.R. Otto teractions. Acetone spray in air is used here for convenience of Page: 255-258, Paper no. 254, Paper Code: BL21 diagnostics. The phase-Doppler anemometry (PDA) technique is Abstract: Curved mixing layers support instabilities in the form employed to record droplet quantities while laser-induced fluores- of longitudinal vortices aligned in the direction of the flow; these cence (LIF) imaging is applied separately to obtain acetone vapour are similar to the Görtler vortices known to exist in curved bound- data. ary layers. Vortices of a similar ilk are produced by an unstable The combined liquid and vapour mass fluxes of acetone measured temperature stratification. As in Otto, Stott & Denier [8], by mak- at various axial locations in the jet agree satisfactorily with the to- ing the Boussinesq approximation we may study the heated mixing tal mass flow rate of acetone injected. As expected, the mean slip layer without introducing full compressibility. Our study is aimed velocity increases for larger droplets and is found an important mainly at the mixing layer created by a mountain lee wave, and the quantity for the overall evaporation of sprays. The evaporation effects the longitudinal vortices have upon the flow. rate increases significantly with decreasing Sauter mean diameter If one plots a neutral curve in the wavenumber-Görtler number of droplets. More research is needed to quantify these effects re- (G, representative of the level of curvature) plane, two regimes are sulting in an improved droplet evaporation model. apparent downstream. One is an inviscid area of growth where G 1 and the spanwise wavenumber is O(1). Here, inviscid vor- Hydrocarbon Fuelled Pulse Detonation Engine Anal- tices develop over short streamwise distances and are governed by ysis a modified form of the Taylor-Goldstein equation. In the second Con Doolan Page: 271-274, Paper no. 63, Paper Code: CO02 region, known as the right-hand branch, the wavenumber is also large and viscous effects become important. Abstract: A multiple combustor pulse detonation engine concept is analysed using a fourteen species chemical equilibrium model. A Correct Model of Variance, Skewness, Kurtosis in Results are coupled with an analytical two-dimensional supersonic Boundary Layer with Turbulent External Layer inlet model to provide estimates of operational performance. The Paola Gualtieri, Guelfo Pulci Doria analysis provides preliminary engine sizing and operational infor- Page: 259-262, Paper no. 273, Paper Code: BL22 mation of hydrocarbon fuelled pulse detonation engines for fu- Abstract: Boundary layer intermittency is one of the most impor- ture tactical missile systems and boost-phase propulsion for hy- tant and interesting fluid mechanics research topics. Intermittency personic air-breathing engines. refers to the fact that at each point in a flow field, the boundary Modelling of Coal Combustion in Full-Scale Indus- layer is alternately present or absent. The presence percentage of trial Furnace boundary layer at a point is called the intermittency factor I at that Monir Hossain, Jamal Naser point. The I distribution versus distance from the wall is generally Page: 275-278, Paper no. 96, Paper Code: CO03 described in literature by the erf function. If the external layer is turbulent, at each point of the flow statistical quantities values of Abstract: A Computational Fluid Dynamics (CFD) model for sim- fluctuation velocity can be defined (Variance, Skewness, Kurtosis) ulating fluid flow and combustion in industrial scale tangentially which are characteristic either of the instants when the boundary brown-coal fired German Furnace (600MW) is presented in this pa- layer is present or of the instants when the external layer is present. per. The CFX Package (CFX4, 1997) has been used to model this fur- Moreover, direct measurements of these same statistical quantities nace. It consists of Standard k-epsilon turbulence model for fluid give values that depend on previous ones, through not simple ex- flow, Shah’s Discrete transfer Model for radiation, Single-reaction pressions. In this paper these expressions have been fully derived. Devolatilization model for devolatilization, Eddy-break-up model The possibility of using simplified expressions of linear combina- for gaseous combustion, Field’s Model for Char oxidation. The pre- tion, giving as weights I and its complement to one, has also been dicted velocity and temperatures have been validated against the shown. Finally these simplified expressions have been compared available measured data. Reasonably good agreement between the with the more complex general expressions, showing errors in the predicted results and the measured data was obtained. region of 10% maximum. The Impact of Strong Swirl and Buoyancy on the Pressure Fluctuations on Cylinders with Thick Tur- Structure of Turbulent Jets and Flames bulent Boundary Layers in Axial and Near-Axial W. Kollmann, I.M. Kennedy Flow Page: 279-282, Paper no. 117, Paper Code: CO04 F.L. Berera, M.K. Bull Abstract: Jets and flames with strong swirl exhibit recirculation Page: 263-266, Paper no. 280, Paper Code: BL23 that leads to loss of axial momentum and a susceptibility to buoy- Abstract: Results are presented of an investigation of surface- ancy forces for small Mach numbers. The impact of buoyancy on pressure fluctuations beneath turbulent boundary layers, with thick- slightly heated, swirling jets and the effect of radiative heat loss nesses up to 11 times the cylinder radius, on cylinders in axial and on non-premixed, compressible, swirling flames are explored nu- near-axial flow. Attention is concentrated on the power spectrum merically.
8 Flowfield Regimes of Non-Reacting Swirling Flows The Effect of Oxygen Concentration on the Structure Yasir M. Al-Abdeli, Assaad R. Masri of Turbulent Nonpremixed Flames Page: 283-286, Paper no. 141, Paper Code: CO05 B.B. Dally, A.N. Karpetis, R.S. Barlow Abstract: This study is part of larger program aimed at providing Page: 295-298, Paper no. 286, Paper Code: CO09 an improved understanding of reacting and non-reacting swirling Abstract: MILD combustion is a newly implemented and developed flows and at establishing a comprehensive database which will be- concept to achieve high thermal efficiency and fuel saving while come an international benchmark for validating and developing maintaining emission of pollutants at very low levels. It utilizes numerical tools. The focus of this paper is on non-reacting swirling the concept of heat and exhaust gas recirculation to achieve com- flows of air in air obtained at a single jet velocity and for two dif- bustion at reduced temperature, with a flat thermal field and low ferent swirl numbers. Only one co-flowing air stream is swirled. turbulence fluctuations. An experimental burner is used in this Laser Doppler Velocimetry is used to map the three components study. Temporally, and spatially resolved measurements of reac- of velocity, turbulence levels and shear stresses (
9 was selected following grid-independence testing. A segregated where the spanwise average maintains the original symmetry. The solver and a second order discretisation scheme were used for all interaction of these two transitions results in a large number of equations. A comparative assessment of three turbulence mod- complex vortex shedding patterns which were visualised in the ex- els was performed, using: the Reynolds Stress Model-RSM (taken perimental studies of Tatsuno & Bearman [5]. Accurate locations as a benchmark for comparison), the Realisable k-ε (RKE), and of the transitions and the variation of the three-dimensional criti- the Renormalised Group Theory model (RNG). The results showed cal wavelength as a function of KC and β are presented. that the RKE turbulence model performed only slightly better that An Effective Method of Calculating Transonic Flows the RNG model in regions of high swirl, however the RNG model and Wave Drag of Axisymmetric and 3-D Elongate showed closer predictions to the RSM in weaker swirl regions. The Bodies Within Framework of Transonic Equivalence RKE model however converged more rapidly than the RNG hence Rule was selected in all subsequent calculations. A.S. Fonarev, Jehangir T. Madhani, M.A. Naida For reacting flow modelling, turbulence-chemistry interaction was Page: 323-326, Paper no. 74, Paper Code: CF07 accounted for using a β-shaped PDF. The chemistry of the mix- Abstract: A theoretical study of steady transonic flows about ax- ture was represented in the model using an Equilibrium Chemistry isymmetric and 3-D elongate bodies has been carried out within Model (ECM). A look-up table (in mixture-fraction space) was gen- the framework of non-linear small disturbance theory using the erated for gaseous air-ethylene mixture. This mixture was selected transonic equivalence rule. A numerical method for calculating because it reasonably represents the chemistry of a particular DR transonic flow about bodies of revolution was used by formulating solid-fuel, but is much easier to model. The effect of air-fuel mo- the Alterating Direction Method together with monotone Engquist- mentum ratio on flow and combustion characteristics was inves- Osher’s algorithm for the axisymmetric case. This approach has a tigated. It was found that increasing the air-fuel momentum ratio good reputation in solving similar two-dimensional problems. improves the thermal efficiency of the combustor, reduces unburnt fuel, lowers CO emission, but did not have a significant effect on A new effective algorithm to determine wave drag of bodies of rev- flow structure. olution in inviscid transonic flow has been developed. As a result, Three-Dimensional Modelling of a Tsunami Inter- the wave drag value is obtained by velocity jump integration along acting with Real Topographical Coastline Using shocks closing local supersonic regions. This method is more ex- Smoothed Particle Hydrodynamics act then the ordinary method of integration of pressure along the François Debroux, Mahesh Prakash, Paul Cleary body surface. Page: 311-314, Paper no. 55, Paper Code: CF04 The efficiency of a numerical algorithm is demonstrated by calcu- lating transonic flow over thin bodies of revolution. The results Abstract: This paper presents the simulation of a tsunami wave concerning calculations of the wave drag of elongate 3-D configu- interacting with a section of real coastline adapted from the US Ge- rations of hypersonic aircraft in the framework of transonic equiv- ological Survey (USGS). The full Navier-Stokes equations are solved alence rule are also given; these results were derived earlier by using the Smoothed Particle Hydrodynamics (SPH) method. Since A.S. Fonarev and M.A. Naida, whilst working at the Central Aero- the SPH method is mesh free it is well suited to simulating com- hydrodynamic Institute (TsAGI), Moscow, Russia. plex free-surface flows of this kind involving wave propagation, splashing, wave refraction and break up. The full three dimen- Effect of a Downstream Sudden Contraction on Flow sional nature of the simulation allows important features such as Instability Behind a Sudden Pipe Expansion the differential breaking of the wave due to variations in the sea B. Guo, D.F. Fletcher, T.A.G. Langrish bed level, preferential inundation of exposed coastal features and Page: 327-330, Paper no. 83, Paper Code: CF08 wave reflection and refraction. The paper demonstrates the ability Abstract: In this paper, turbulent flow behind a sudden pipe expan- of the SPH method to handle these large geophysical phenomena sion followed by a sudden contraction is numerically simulated, having length scales of the order of kilometres and to be able to in order to investigate the effect of the downstream contraction predict information of importance for coastal defence. on the flow instability in non-swirling flows, as well as in weakly Modelling of the Effect of Concentrated Wall Suc- swirling flows. Calculations are carried out using CFX4.3, in which tion on a Turbulent Boundary Layer Using a Second- the transient RANS approach and the standard k-ε model are im- Order Moment Closure plemented. The diameter ratio for both the expansion and the L. Djenidi, R.A. Antonia contraction is five. The length of the large pipe (normalised by its Page: 315-318, Paper no. 62, Paper Code: CF05 diameter D) is varied in the range from 1.0 to 4.0, and the results are compared with those for the case without a contraction. The Abstract: The present paper reports on a numerical study of a current results show that a sudden contraction tends to stabilise turbulent boundary layer subjected to suction through a spanwise the nonswirling flow when the large pipe length is reduced. How- strip. The main thrust of the work is to assess the performance ever this stabilising effect does not apply to swirling flow, although of a low Reynolds number Reynolds stress model in the context of the precessing direction and frequency are affected significantly. calculating the development of a turbulent boundary layer when it is subjected to what is considered to be a severe change in bound- Modelling of Fluid Flow in a 3-Axial Groove Water ary conditions. The calculation was carried out for two Reynolds Bearing Using Computational Fluid Dynamics R θ numbers, ( θ0 = 850; 0 is the momentum thickness) and two suc- R. Pai, D.J. Hargreaves , R. Brown tion rates ( σ = 1.3 and 2.6). With reference to measurements, the Page: 331-334, Paper no. 86, Paper Code: CF09 following effects are reproduced reliably by the calculation: (i) de- Abstract: This paper details a Computational Fluid Dynamics ap- pendence of the skin friction coefficient with respect to Rθ and 0 proach to model fluid flow in a journal bearing with three equi- σ , (ii) dependence of the mean velocity and Reynolds stresses dis- spaced axial grooves and supplied with water from one end of the σ tributions on , and (iii) faster recovery of the near-wall region of bearing. In the clearance space of the bearing, water is subjected the boundary layer relative to that of the outer layer. to both velocity and pressure induced flow. A dedicated Compu- The Transition to Three-Dimensionality in the Flow tational Fluid Dynamics software has been used to model the fluid Produced by an Oscillating Circular Cylinder flow phenomenon. Results are presented for the circumferential J.R. Elston, J. Sheridan, H.M. Blackburn and axial pressure distribution in the bearing clearance for differ- Page: 319-322, Paper no. 69, Paper Code: CF06 ent loads, speeds and supply pressures. Results are compared with experimentally measured pressure distributions. Abstract: The stability of the flow generated by a cylinder oscillat- ing in quiescent fluid is investigated using direct numerical sim- Merger of Stretched Vortices at High Reynolds Num- ulation and Floquet analysis. This study determines transitions ber between flow regimes as functions of the dimensionless oscilla- K. Higgins, A. Ooi, M.S. Chong tion amplitude (Keulegan-Carpenter number, KC) and frequency Page: 335-338, Paper no. 89, Paper Code: CF10 β KC β (Stokes number, ). At low values of and the flow is two- Abstract: In this paper, we present a numerical study of the merger dimensional and has a reflection symmetry about the axis of os- of two Burgers vortices in an axisymmetric strain field at a Reynolds KC β cillation. Increasing or causes either of two distinct tran- number of 5000. Various features of the evolution are examined, sitions to three-dimensional flow. The two transitions are either such as the flow topology, dissipation field and evolution of az- a breakage in the reflection symmetry accompanied by a three- imuthal modes. dimensional transition or a transition to three-dimensional flow
10 A New NVD Scheme in Pressure-Based Finite Vol- A Three-Dimensional Simulation of Temperature ume Methods and Water Vapor Distributions Between a Heat M.H Djavareshkian Source and a Ventilating Hood Page: 339-342, Paper no. 107, Paper Code: CF11 C.P. Tso, S.C.M. Yu, P.C. Chia, K. Sundaravadivelu Abstract: The paper presents an implementation of a new NVD Page: 355-357, Paper no. 114, Paper Code: CF15 scheme into an implicit finite volume procedure, which uses pres- Abstract: Numerical simulation of air motion inside a kitchen is sure as a working variable. This scheme with the minimum num- carried out in the presence of heat generation associated with the ber of adjustable parameters is robust and does not create con- cooking process. A preliminary analysis on the heat removal ca- vergence problems on the wide range of test cases. The method pability is conducted under different capture velocities of the ven- is applied to the computation of steady transonic and supersonic tilating hood. A critical hood capture velocity is determined to flows over bump in-channel geometry as well as to the transient provide a minimum requirement for efficient removal of heat and shock-tube problem. The results are compared with other compu- thus provide thermal comfort in the kitchen. A detailed investi- tations published in the literature. gation of the make-up air arrangements, radiation effects, effluent Flow Past Elliptical Cylinders at Low Reynolds Num- transport is under progress and will be discussed during the pre- bers sentation. S.A. Johnson, M.C. Thompson, K. Hourigan Two- and Three-Dimensional Temperature Struc- Page: 343-346, Paper no. 108, Paper Code: CF12 tures in a Shallow Wedge Subject to Solar Radiation Chengwang Lei, John C. Patterson Abstract: The vortex structures behind 2D elliptical cylinders at Page: 359-362, Paper no. 135, Paper Code: CF16 low Reynolds numbers were investigated for a Reynolds numbers range of 30 to 200. By varying the aspect ratio of an elliptical Abstract: The temperature structures in a water-filled shallow wedge cylinder, the geometry varies between the extremes of a circular subject to solar radiation obtained from two-dimensional (2-D) and cylinder and a flat plate normal to the flow. It is ascertained that three-dimensional (3-D) simulations are presented in this paper. as the aspect ratio is decreased, the shedding behind the elliptic The 3-D results show that the flow experiences a transition from cylinder changed from steady Karman vortex shedding to a sur- 2-D to 3-D as it passes through three stages of the flow develop- prising different flow with two distinct regions. The first region ment. A comparison between the 2-D and 3-D results indicates that situated directly behind the cylinder contained two rows of vor- the 2-D simulation reproduces major flow features at all stages ir- tices rolling up from the cylinder with a region of relatively dead respective of the three-dimensionality. flow in between. A convective instability in the flow further down- Navier-Stokes Simulation of 2-D Unsteady Aerody- stream causes the two rows of vortices to interact strongly and namics of a Turbine Cascade results in the formation of downstream secondary vortices. It is I.W. McBean, F. Liu, K. Hourigan, M.C. Thompson found that at the transition Reynolds number between the normal Page: 363-366, Paper no. 150, Paper Code: CF17 Karman vortex wake and the occurrence of secondary vortex shed- k − ω ding, there is a peak in the Strouhal number for a given aspect ratio Abstract: A Navier-Stokes solver coupled with the turbu- as well as a local minimum in the drag coefficient. Furthermore, lence model is developed to solve the unsteady flow through an the value of the Reynolds number at the onset of periodic vortex oscillating turbine cascade. Calculations are performed in parallel shedding decreased as the aspect ratio decreased. in a time-accurate manner. A coupled simulation is performed for the Isogai wing model. The Generation and Suppression of Vortex Break- down by Upstream Swirl Perturbations Large Eddy Simulation of Transient Ceiling Jet in a M.C. Jones, K. Hourigan, M.C. Thompson Compartment Fire Environment Page: 347-350, Paper no. 110, Paper Code: CF13 V. Novozhilov Page: 367-370, Paper no. 168, Paper Code: CF19 Abstract: While a mechanism for vortex breakdown has not yet been comprehensively described, efforts have been made to ob- Abstract: Development of a ceiling jet is a primary feature of a tain some control over breakdown in flows of practical interest. compartment fire. This phenomenon is caused by the buoyant fire In this study the response of breakdown in one geometry to dis- plume hitting the ceiling of the compartment and spreading along turbances of varying magnitudes is investigated computationally. it. The parameter space studied corresponds to the region in which In the present study, jet front propagation along the ceiling is pre- hysteresis occurs; here the possibility of suppression or instigation dicted using the Large Eddy Simulation (LES) method. The pre- of breakdown within this region is explored, through the introduc- dicted propagation rate is in good agreement with the available ex- tion of an upstream disturbance to the flow. Results indicate that perimental data. Results of LES simulation are also compared with a jump to and from conjugate breakdown/non-breakdown states the conventional Reynolds-Averaged Navier-Stokes (RANS) predic- can be provoked through judicious application of a transient im- tions and correlations based on dimensional analysis. pulse. An Investigation of the Relationship Between Flow Toward a Geometry Independent Criterion for Vor- Topology and the Distribution of a Passive Scalar in tex Breakdown Isotropic Turbulence M.C. Jones, K. Hourigan, M.C. Thompson P.L. O’Neill, J. Soria Page: 351-354, Paper no. 111, Paper Code: CF14 Page: 371-374, Paper no. 169, Paper Code: CF20 Abstract: The observation of vortex breakdown over delta wings, Abstract: Data obtained from direct numerical simulations of iso- in swirling pipe flows, and in torsionally driven cylinders, has led tropic homogenous turbulence and the distribution of a passive to inconsistencies regarding the definition of breakdown and an scalar with an applied mean gradient is analysed using the topolog- inability to define a geometry independent criterion for the oc- ical techniques developed by Chong, Perry and Cantwell [1]. Sev- R currence of breakdown. Study of two geometries which produce eral simulations were run at various values of eλ and Schmidt vortex breakdown, the swirling pipe flow and torsionally driven number (Sc ). Comparing the numerical results obtained, some re- cylinder flow, has resulted in revised definitions of the quantities lationships between the scalar characteristics and the topological generally used to specify breakdown flows: the Reynolds number features in the flow have been identified. Results from this work (Re) and swirl parameter (S or Ω). A consistent way of defining may be useful in the development of improved mixing processes these quantities is presented, with the aim of comparing more di- by isolating the effect of the various topological features in the rectly the manifestations of breakdown in the various geometries flow on the distribution of a passive scalar. in which it is observed. Both quantities are based on the axial and A Numerical Study of Swirling Vortex Rings azimuthal velocity profiles measured in the vortex core, and hence A. Ooi, J. Soria, T.T. Lim, W. Kollmann, M.S. Chong are geometry independent. Page: 375-378, Paper no. 172, Paper Code: CF21 Abstract: The evolution of the axisymmetric swirling vortex ring is studied by solving the Navier-Stokes equations in cylindrical co- ordinates. Simulations were carried out at various Reynolds num- bers, Re, and swirl numbers, S. It was found that the propagation velocity of the vortex ring decreases with increasing S. It is shown
11 that this is due to the presence of secondary vorticity at the front Mathematical Modelling of Magnetic Flow Control in of the ring which is of the opposite sign to the primary vortex ring. a Single Belt Caster S.H. Seyedein, M.R. Aboutalebi Three-Dimensional Modelling of Dam-Break In- Page: 395-399, Paper no. 211, Paper Code: CF26 duced Flows Using Smoothed Particle Hydrodynam- ics Abstract: Near-net shape casting has been the subject of so many Mahesh Prakash, François Debroux, Paul Cleary researches during the past decades where the major ones dealt with strip casting processes. One of the distinguished techniques Page: 379-382, Paper no. 185, Paper Code: CF22 developed in early 80’s, is the single belt strip casting process in Abstract: This paper presents simulations of dam-breakage using which liquid metal is introduced onto a moving water-cooled belt. real topography obtained from the US Geological Survey (USGS). The most important aspect of this process which has a crucial ef- Three-dimensional simulations were performed using the full Navier- fect on product quality, is metal delivery system. The main point Stokes equations with the particle-based Lagrangian Smoothed Par- in this regard is to get the melt run out evenly onto the conveyor ticle Hydrodynamics (SPH) method. Since SPH is mesh free it is belt at the correct thickness, which can be handled by flow control well suited to simulating free-surface flows of this kind, involving from feeding system. splashing and fluid layer break up. This paper demonstrates the ability of the SPH method to handle these large geophysical phe- In the present work, a DC magnetic brake was considered to be nomena having length scales of the order of kilometres. Due to used to control the flow in the downstream of the mold. This computational limitations, the highest resolution for which simu- study presents some numerical results obtained from mathemati- lations were carried out used a particle separation of around 6.0 cal modeling of a typical single belt caster. The coupled turbulent m for a topographic area of approximately 15 sq km. An example flow and heat transfer as well as magnetic field effects were con- k − ε of a potential dam breakage flow, and its interaction with the sur- sidered in this model. A low-Re turbulent model was used rounding topography, is presented here. to account for the turbulent effects. The transport equations were solved using finite volume method on a staggered grid domain. Flow Transition in the Wake of a Rotating Sphere Parametric studies were performed in this study to evaluate the C.J. Pregnalato, M.C. Thompson, K. Hourigan effect of casting conditions and magnetic field intensity on fluid Page: 383-386, Paper no. 187, Paper Code: CF23 flow and temperature fields. Abstract: The flow past a rotating sphere is investigated numer- A Numerical Study of Bluff Ring Wake Stability ically using a three-dimensional spectral element/spectral direct G.J. Sheard, M.C. Thompson, K. Hourigan numerical simulation. The effect of sphere rotation on transition Page: 401-404, Paper no. 213, Paper Code: CF27 regimes is analysed for Reynolds numbers of 10 < Re < 500, where Abstract: A numerical study of the wake dynamics and stability Re is the Reynolds number based on freestream velocity U, sphere of the flow around bluff rings placed normal to the flow direction diameter d and kinematic viscosity ν. The results show that the at low Reynolds number is presented. An attractive feature of this Reynolds numbers for the first transition to three-dimensionality, bluff body geometry is that it effectively behaves locally like a circu- Re , and the second transition to time-dependence, Re , are func- 1 2 lar cylinder at high aspect ratio while, as the aspect ratio is reduced tions of the angular velocity of the sphere Ω (normalised by the to zero, the body is transformed to a sphere. Thus, it covers a rich sphere radius and freestream velocity). The effect of non-streamwise diversity of wake topologies and transitions. A spectral-element sphere rotation is to reduce the critical Reynolds numbers at which method is used to solve the unsteady axisymmetric Navier-Stokes transition first occur. However, rotation about the streamwise axis equations governing the fluid flow. Wake stability is determined results in a delayed transition, due to the suppression of the out- using a linear Floquet-type stability analysis. Strouhal-Reynolds of-plane velocity component which is thought to trigger the flow number profiles are provided for a range of ring aspect ratios, transition. as are critical Reynolds numbers for the onset of flow separation Three Dimensional Flow Development in the Wake and periodic flow. A decrease in shedding frequency and an in- of Elongated Bluff Bodies crease in the critical Reynolds numbers for separation and un- Kris Ryan, M.C. Thompson, K. Hourigan steady flow with decreasing ring aspect ratio is shown. Stability Page: 387-390, Paper no. 203, Paper Code: CF24 analysis has enabled interesting flow features with respect to the Abstract: The results from Floquet stability analysis of the flow three-dimensionality of the flow to be obtained for different ring around nominally two-dimensional long plates with elliptical lead- aspect ratios. ing edges and blunt trailing edges are presented, elucidating the Quasi-Consistence Hexahedral Element Method for early stages of wake transition to turbulent flow. Three modes Three-dimensional Convection Problems of instability are found: Mode A, Mode B and a period doubling Shiqiang Wu, Daoyang Ding, Jinpei Liu mode. The first two of these also occur in wake transition for Page: 405-408, Paper no. 215, Paper Code: CF28 circular cylinders and square cross-sectioned cylinders. For suf- ficiently large aspect ratio, Mode B is found to be the dominant Abstract: The key to the numerical solution of three dimensional instability mode. This research indicates the generic turbulence convection problems is to search for a high-precision interpolat- transition scenario suggested for circular twodimensional bodies ing function, which can keep the result stable and damping low. does not apply to all two-dimensional bluff bodies. Based on the consistence hexahedral element method, an advanced quasi-consistence hexahedral element method for three-dimensional Spectral Element Based Dynamic Large Eddy Simu- convection problems is developed in this paper. The flow domain lation of Turbulent Channel Flow is discretized into arbitrary hexahedral elements, which do not S. Schmidt, H.M. Blackburn change with time. A cubic polynomial based on three-dimensional Page: 391-394, Paper no. 207, Paper Code: CF25 Cartesian coordinates (x,y,z) is adopted as the element interpolat- Abstract: In this study the dynamic Smagorinsky model (DSM) has ing function to ensure that variable functions and their first deriva- been incorporated into a spectral element method and applied in tives over the entire domain are continuous. The verified results a large eddy simulation (LES) of a turbulent channel flow. The show that this algorithm is more precise than other methods. dynamic procedure estimates the parameter of the Smagorinsky CFD Code Benchmark on Void Fraction Distribution model (SM), thereby allowing for an adaption of the mixing length in Subcooled Flow Boiling of a Concentric Annular to the local turbulent state during the simulation. As expected, Tube at Low Pressure strong fluctuations of the dynamic estimate arise which are due to Denpong Soodphakdee, J.Y. Tu, Masud Behnia the local nature of the model. To avoid any adverse influence to the Page: 409-412, Paper no. 222, Paper Code: CF29 convergence of the numerical scheme, most of these fluctuations are dampened out by averaging along the spanwise (homogeneous) Abstract: In a comparison exercise, three CFD codes, i.e. CFX-4.2, direction and in time. Two different test filter kernels have been FLUENT 4.5, and RELAP 5/MOD2, were used for the simulation of used in order to assess the quality and the robustness of the dy- subcooled flow boiling in a vertical concentric annular tube. The namic procedure and shed light on the dependency of the whole numerical predictions from these three codes were compared with model on the test filter. The simulation results provide a good experimental void fraction distribution. The available bubble size overall agreement with both experimental data and previous LES correlations were adopted into the two-fluid model of CFX-4.2. The results, obtained with the fixed-constant Smagorinsky model. adjustable parameters of the evaporation-condensation model of FLUENT 4.5 were modified. Surface heat flux, subcooled tempera- ture, water flow rate and system pressures were varied to check the
12 capability of each code at different conditions. The predicted void Large Eddy Simulations of Plane Turbulent Imping- fraction distribution results shows that the 1D code RELAP 5 gives ing Jets less accurate results compared with the modified general purpose François Beaubert, Stéphane Viazzo codes. The more complex two-fluid model of CFX offers the most Page: 425-428, Paper no. 247, Paper Code: CF33 consistency of the void fraction distributions for the whole range Abstract: Large Eddy Simulation of plane turbulent impinging jets of study, but under predict in the high subcooled region. The sim- have been used to help improve the design of air curtains. Statis- ple model of FLUENT predicts the void fraction in a relatively low tical quantities and the dynamics of the jet are studied. The sta- Reynolds number range. tistical analysis lies on the mean and rms quantities along the jet Adaptive Electromagnetic Control of Artificially In- axis. The dynamics of the jet is explored using the instantaneous duced Disturbances velocity, vorticity and low pressure fields. A spectral analysis is E.C. Spong, J.A. Reizes, E. Leonardi also performed. Page: 413-416, Paper no. 226, Paper Code: CF30 Finite Element Modeling of Generalised Newtonian Abstract: A numerical simulation of the control of artificially in- Flows duced disturbances over a single electromagnetic tile is presented. W. Barth, G. Carey, S. Chow, B. Kirk The tile consists of a pair of magnets and electrodes and is oper- Page: 429-431, Paper no. 277, Paper Code: CF34 ated in a weakly conducting fluid as both a flow sensor and actu- Abstract: Here we consider finite element modeling of coupled ator. The tile is located beneath the lower wall of a channel con- flow and heat transfer for Eyring-Powell and Williamson general- sisting of two free slip non permeable walls which are infinite in ized viscosity models. Supporting numerical studies are provided extent in the cross flow direction. Time varying sinusoidal vertical using a domain-decomposition approach for simulations on a Be- velocity disturbances are imposed on a uniform flow at the chan- owulf cluster. nel entrance and convected downstream. As a result a sequence of upward and downward vertical velocities are passed over the Diverse Fluid Mechanics Topics tile. The control objective is to dampen the upward velocity dis- On the Relationship Between Large-Scale Forcing turbances as they pass over the tile while leaving the downward and Small-Scale Statistics in Decaying Grid Turbu- velocity disturbances unhindered. The dampening of the upward lence velocities loosely approximates the control of the ejection events F. Anselmet, R.A. Antonia, L. Danaila, T. Zhou of a turbulent boundary layer. For an arbitrary sequence of dis- Page: 433-436, Paper no. 5, Paper Code: OT01 turbances a control algorithm continually varies the Lorentz force strength as a function of the instantaneous velocity field. This in- Abstract: For moderate Reynolds numbers, the isotropic relations formation, in conjunction with the modeled responses of the sen- between second-order and third-order moments for temperature sor, is then used to train a neural network. The neural network has (Yaglom’s equation) or velocity increments (Kolmogorov’s equa- demonstrated its ability to control other sequences of artificially tion) are not respected, reflecting a non-negligible correlation be- induced disturbances of a similar nature. tween the scales responsible for the injection, the transfer and the dissipation rate of turbulent energy. For grid turbulence, the Multi-Fluid Multi-Dimensional Numerical and Exper- dominant large-scale phenomenon is the non-stationarity (or, in an imental Investigation of Dispersed Two-Phase Flow experimental context, the streamwise non-homogeneity) of statis- with Wall Liquid Film in the Vicinity of Obstacles tical moments resulting from the decay of energy downstream of Zoran V. Stosic, Vladimir D. Stevanovic, Akimi Ser- the grid. The objective of our paper is to quantify the influence izawa of this non-homogeneity on various properties associated with the Page: 417-420, Paper no. 229, Paper Code: CF31 inertial and dissipative ranges of scales. In particular, we will show Abstract: Annular two-phase flow around an obstacle in a vicinity that a new term must be added to Yaglom’s and to Kolmogorov’s of the channel wall is numerically and experimentally investigated. equations to account for the decay of second-order moments and Numerical simulations of gas phase, entrained droplets and wall thus explain the observed departure of the inertial range from the liquid film flows were performed with the three-fluid model and isotropic ’4/3rds’ and ’4/5ths’ laws. Similar contributions must with the application of the high order numerical scheme for the also be retained in the isotropic forms of the budget equations for liquid film surface interface tracking. Predicted are a separation the mean dissipation rates εθ and ε . One of the inferences from of gas and entrained droplets streams around the obstacle, as well our work is that the reported non-universal inertial-range proper- as a change of wall liquid film thickness in the vicinity of obsta- ties are most often a result of the large-scale influence rather than cle. Results on liquid film dynamic behaviour are compared with an indication of strong departure from isotropy. the recently obtained experimental results [4]. Multi- dimensional Simulation and Scaling of Unstable Natural Convec- characteristics of surface waves on the liquid film were measured tion Flow in Stratified Open Cavities with newly developed ultrasonic transmission technique in a 3x3 S.W. Armfield, A. Javam rod bundle test section with air-water flow under atmospheric con- Page: 437-440, Paper no. 6, Paper Code: OT02 ditions. Obtained numerical results are in agreement with experi- mental observations. Presented investigation gives insight into the Abstract: Cavity flow with a heated vertical wall facing an open complex mechanisms of separated two-phase flow with wall liquid boundary with top and bottom impervious and adiabatic and back- film around the obstacle. The obtained results are a support to ground stratification exhibits a characteristic bifurcation in the thermal-hydraulic design and safety analyses of various thermal downstream region of the thermal boundary layer. The bifurca- equipments. tion has been shown to be associated with the free jet produced by the downstream turning boundary layer flow. The open cav- 3D Propagation of CHF/Rewet Front within Rod ity bifurcation is similar to that observed in closed cavities with Bundle in Turbine-Trip-w/o-Bypass Simulation: Ex- heated and cooled opposing walls and in that context it has been perimental and Numerical Investigation Based on suggested that the bifurcation instability is shear driven and corre- Porous Media sponds to the well known instability of a Bickley jet. Results for a Zoran V. Stosic, Vladimir D. Stevanovic, Tadashi Iguchi range of Rayleigh number have been obtained allowing the thermal Page: 421-424, Paper no. 230, Paper Code: CF32 boundary layer exit jet to be scaled. It is also shown that the exit Abstract: Investigation based on experimental and numerical sim- jet may be shifted from the upper boundary by changing the ambi- ulation of three-dimensional transient propagation of a dry-out ent stratification, while retaining the general form and bifurcation front within a nuclear fuel rod bundle is performed. It is observed behaviour, showing that the bifurcation is not dependent on the that CHF and rewetting took place at several elevations where the presence of the upper boundary. spacers are located. Spreading of CHF across a bundle caused by Leakage Flow and Shear Stress in the Clearance Gap power increase is quantified and the locus of the dry patches is of a Heart Pump Model shown. Due to possible building of vapour zone the CHF spatial L.P. Chua, K.S. Ong, T. Zhou, S.C.M. Yu propagation has to be carefully analysed in transients. Page: 441-444, Paper no. 44, Paper Code: OT03 Abstract: This study presents an estimation of the leakage flow through the clearance gap between the impeller and the stationary casing of a centrifugal heart pump model and the shear stress dis-
13 tribution inside the gap. From the velocity field measurements that servation and stabilization. have been done in the clearance gap [1,2], the volumetric flowrate Surface Solidification in Open Channel Flow inside the gap could be roughly estimated. With the velocity pro- Ross W. Griffiths, R.C. Kerr, K.V. Cashman files obtained, the leakage flow through the clearance gap was Page: 461-464, Paper no. 80, Paper Code: OT08 found to be about 0.000944 m3/s and 0.000766 m3/s by numerical integration, which has caused about 20% to 30% losses of the inlet Abstract: The solidification of channel flows that are cooling from flow depending on the flow conditions. This first time experimen- their surface is studied in experiments in which polyethylene gly- tally measured leakage flow for this blood pump is consistent with col wax flows under cold water down an inclined, open channel of the finding of Yamada et al. (1997)[3]. From the velocity profiles, rectangular cross-section. We find two regimes, depending on the the shear stress distributions can also be obtained. It is found that flow velocity and on the temperatures of the wax and the water the highest shear stress is 206 Pa, which is far below the hemolysis relative to the freezing temperature of the wax. For sufficiently threshold value of 400 Pa suggested, by Sallem and Hwang (1984). high flow speeds and temperatures, a solid surface crust develops in the centre of the channel some distance from the source. The Measurements of Gap Velocity in a Heart Pump crust remains separated from the walls by crust-free shear regions Model as it is carried down the channel. Under these conditions solid- L.P. Chua, K.S. Ong, S.C.M. Yu, W.K. Chan , Y.W. Wong ification also occurs very close to the source within the sidewall Page: 445-448, Paper no. 45, Paper Code: OT04 boundary layers, where the solid phase is continually sheared and Abstract: Animal trials of the Kyoto-NTN Magnetically Suspended broken into small pieces. At lower flow speeds and temperatures Centrifugal Blood Pump (MSCP) showed that hemolysis and throm- the solid creates a stationary roof and flow continues through an bosis were prevalent in the clearance gaps between the impeller insulated channel beneath. shroud surfaces and pump casing. This paper presents the mea- Redesigning the Rotor Fan Blades to Improve the surement of the velocity in the clearance gap of a 5:1 model of the Cooling of Roxburgh’s Hydro-Generators pump. The velocity vector distributions show that the double vo- B. Liddell, A. Tucker, I. Huntsman, M. Manders, C. Mc- lute design of the pump, especially the splitter plate that started at Donald ◦ θ = 180 has created a washout mechanism in the clearance gap. Page: 465-468, Paper no. 101, Paper Code: OT09 These have suggested that hemolysis and thrombus formations are Abstract: Since 1995, the level of air flow within the hydro-gen- minimal and hence the pump is able to function nominally efficient erators at Roxburgh Power Station has been insufficient to main- as compared to other centrifugal pumps. tain stator winding temperatures below maximum allowable limits Transient Flow in a Ventilated Enclosure Containing from January-April. In the past this has resulted in the de-rating a Vertically Distributed Source of Buoyancy of the machines by 12.5% and substantial loss of revenue. The Paul Cooper, Gary R. Hunt, Paul F. Linden objective of this research was to implement a cost effective de- Page: 449-452, Paper no. 51, Paper Code: OT05 sign change to increase the air flow rate past the stator windings Abstract: An experimental and numerical investigation of the fluid without significantly adding to windage losses. A combination of mechanics within an enclosure containing a plane, vertically dis- experiment and 2D and 3D computational fluid dynamics (CFD) tributed source of buoyancy is described. Two separate situations modelling was used to investigate the existing air flow and high- are considered in which the enclosure is either sealed or naturally light possible solution strategies. Based upon the results of these ventilated. In the sealed enclosure the stratification develops in investigations the redesign of the rotor fan blades was chosen as qualitatively the same way as for a ’filling’ box containing a single, the best solution. The 3D CFD models were then further developed point source of buoyancy on the floor. In the case of the ventilated to determine a suitable form for the new fan blades. Calculations box it is found that for some values of non-dimensional vent area made to evaluate the relative performance of the redesigned fan a complex stratification develops with a number of distinct layers blades indicated a 40% greater pressure boost, a reduction in local fed by horizontal intrusions from the vertical source. We present viscous losses from 60%-40% of pumping power, but a 10% increase results from saline solution experiments and compare them with in local windage losses, compared with the original blades. a theoretical model developed using plume theory. Numerical so- Influence of Electromagnetic Field on the Capillary lutions to the theoretical equations which provide detailed infor- Flow Between Parallel Plates mation on the transient development of the density profile within K. Sundaravadivelu, C.P. Tso the enclosure are also presented. Page: 469-471, Paper no. 113, Paper Code: OT10 Natural Ventilation of a Side-Vented Enclosure Con- Abstract: The influence of electromagnetic field on the surface ten- taining a Source of Welding Fume sion driven capillary flow between two parallel plates is investi- G. Slater, Paul Cooper , J. Norrish gated with special reference to MEMS. Analytical solutions are ob- Page: 453-456, Paper no. 52, Paper Code: OT06 tained for different values of the non-dimensional parameters that Abstract: This paper presents a theoretical model of the fluid me- represent the physics of the problem. It is inferred that the appli- chanics of a naturally ventilated enclosure containing a point source cation of electric current in the presence of relatively low magnetic of buoyancy and contamination which is vented to through a sin- field strength may be used to optimize the fluid flow characteris- gle opening on a vertical wall. This represents part of an ongoing tics. Thus one may overcome partial curing of liquid epoxy during study to determine the distribution of welding fume within an en- the underfill encapsulation process and dry-out phenomena oc- closure and how exposure of the welder to the weld fume might curring in micro-channel cooling devices used especially in space be effectively controlled. The welding source generates a buoyant thermal management. plume that rises and slowly fills the confined space with contam- Estimation of Blast Overpressure from a Cylindrical inated air. The mixing of the contaminant within the enclosure is Charge Using Time of Arrival Sensors complex due to the dense inflow through the side opening. G. Katselis, J.G. Anderson A mathematical model of this problem is presented which has simi- Page: 473-476, Paper no. 115, Paper Code: OT11 larities to the classic "filling box" analysis but is substantially modi- Abstract: Time of arrival data for a blast wave generated by a cylin- fied to account for the exchange flow through the vent. Theoretical drical high explosive charge is presented and analysed to provide predictions of the critical vent area required to prevent the buoy- peak static overpressure as a function of distance from the charge. ant contaminated layer of fluid descending below the vent are pre- Comparison of the calculated pressure with measured peak pres- sented together with a discussion of previous research by others on sure shows a close agreement. The advantage of using time of related problems. Results from preliminary experiments and the arrival data is that peak pressures can be determined at very close practical implications of our theoretical model are also discussed. distances from the charge. A Fully Implicit Particle-in-Cell Method for Granular Theoretical and Experimental Modelling of Thermal Flows Erosion by Laminar Lava Flows S.J. Cummins, J.U. Brackbill R.C. Kerr Page: 457-460, Paper no. 53, Paper Code: OT07 Page: 477-480, Paper no. 118, Paper Code: OT12 Abstract: An implicit-in-time method for granular materials is de- Abstract: Thermal erosion by hot lavas during their laminar flow scribed. The method combines the Material Point Method (MPM), over cold ground is investigated both theoretically and experimen- and a Newton-Krylov equation solver to give improved energy con- tally. An analysis of the steady forced convective heat transfer by a
14 laminar channel flow at large Péclet numbers is presented, which is A Study of Volute Tongue and Passage Design on used to determine the final steady-state erosion velocity as well as the Performance of Centrifugal Turbomachines the thicknesses and timescales of the associated thermal bound- K. Miyanaga, T. Kobayashi, T. Ichimiya, T. Sakai, A. ary layers in both the lava and ground. The initial transient period Whitfield involving the growth and remelting of a basal chill layer is also Page: 493-496, Paper no. 204, Paper Code: OT16 quantified. Laboratory experiments are described in which hot, Abstract: The performance of six fan volutes have been investi- molten wax .owed over and thermally eroded an underlying bed gated experimentally using a large-scale model of an overhang tur- of solidified wax. The experimental observations of chill forma- bocharger compressor volute. Three-hole and five-hole yaw probes tion and thermal erosion are found to be in excellent agreement were used to obtain detailed measurements in the diffuser and vo- with the theoretical predictions. The theory also predicts rates of lute. The investigation studied the impact of the size of the re- thermal erosion consistent with those observed in recent flows of circulation port and the design of the tongue on the performance basaltic lava in Hawaii. of the volutes. It is shown that performance was improved by the PIV Study of Lubricant Flow in Journal Bearing Sup- introduction of the re-circulating port. A modified volute design ply Pocket procedure that was applied to two of the designs did not lead to P.B. Kosasih, A.K. Tieu, E.B. Li improved performance. It was shown that the shape of the tongue Page: 481-484, Paper no. 127, Paper Code: OT13 leading edge had an impact on performance particularly at high flow rates. Abstract: Lubricant flow field in a rectangular journal bearing sup- ply pocket using PIV technique has been measured. The obtained Stability of Taylor-Couette Flow with Axial Flow experimental flow field marks a significant step toward validation W.H. Tan, K.D. von Ellenrieder, T.T. Lim, J. Soria of computational result in lubrication analysis. In the present work Page: 497-500, Paper no. 250, Paper Code: OT18 the comparison shows close agreement between the experimental Abstract: This paper describes an investigation, which uses a torque- and computational results in the area covered by the PIV image. measurement technique, of effects of axial flow on the stability Due to the difficulty in accessing the flow area, to obtain flow field of Taylor-Couette flow. Two radius ratios, 0.846 and 0.956, are image in the rectangular pocket, an endoscope was attached to the used. The preliminary results show that the critical Taylor num- CCD camera. The distorted image due to the endoscope optics ber for the onset of Taylor vortices increases monotonically with causes inaccurate magnitude, direction and positions of velocity the Reynolds number of the axial flow and asymptotes to a con- vectors. Therefore to accurately determine the quantitative value stant value. Although our findings are in good agreement with of the velocity vectors and their positions, correction procedure previously published results, which were obtained with either flow must be applied. The paper demonstrates the use of PIV on dif- visualization or pressure measurements, there are some noticeable ficult geometrical configuration and proposes a correction proce- differences with earlier studies. dure when an endoscope is used. The paper is also aimed to shed some knowledge about flow field in journal bearing supply pocket, Experimental Techniques which is useful for the bearing performance analysis. Measurement of Flow-Induced Pressures on the Sur- Convective Circulation Driven by a Non-Uniform face of a Model in the AMRL Water Tunnel Bottom Heat Flux and a Localised Salinity Flux Lincoln P. Erm Julia C. Mullarney, Ross W. Griffiths, Graham O. Page: 501-504, Paper no. 70, Paper Code: ET02 Hughes Abstract: Flow-induced pressures on the surface of a model in Page: 485-488, Paper no. 160, Paper Code: OT14 a flow-visualization water tunnel are extremely small due to the Abstract: The thermal convection in a basin driven by a horizontal low free-stream velocities generally used in such a tunnel. For a variation of surface temperature was originally proposed by Stom- free-stream velocity of 0.1 m/s, flow-induced pressures are typi- mel [11] and Rossby [7] as a useful, simple model of thermohaline cally less than about 15 Pa. In the past the pressures could not circulation in the oceans. We return to the problem and report ex- be measured accurately since suitable pressure transducers were periments in which we impose a uniform heat flux into a long tank not available. In this report, it is shown that it is now possible over one half of its base and cool the other half, achieving large to measure the pressures using a modern highly-sensitive trans- Rayleigh numbers and small aspect ratios. A stable thermocline ducer. Flow-induced pressures were measured on a delta wing in over the cooled base flows towards the heated end, where for suf- the AMRL flow-visualisation water tunnel, and at the same time ficiently large Rayleigh numbers it is eroded by a convective mixed the vortical flow over the wing was visualized, enabling the load- layer that deepens towards the heated (’polar’) end of the basin. ing on the wing to be interpreted in relation to the observed flow We also add to the thermal convection a stabilising salinity buoy- patterns around the wing. This is believed to be the first time that ancy flux imposed at one end of the basin, mimicking a freshwater flow-induced pressures have been measured on a model in a flow- buoyancy flux into polar oceans. Large steady salt fluxes lead to a visualization water tunnel at such a low flow velocity. permanent layering and cessation of deep convection. For smaller Residual Swirl in Axial-Flow Pump salt fluxes we observe a periodic breakdown of a ’polar’ halocline H.S. Parmigiani, A. Revel, B.P. Huynh and an oscillation in the strength of the localised deep convection. Page: 505-508, Paper no. 102, Paper Code: ET03 Low Froude Number Frequency Response of the Abstract: Measurements of residual swirl in an industry-size axial- Wake for Flow Past a Cylinder Close to a Free Sur- flow pump unit have been conducted, using a Fechheimer probe. face They reveal that even though the unit’s components have been P.J. Reichl, K. Hourigan, M.C. Thompson constructed according to well established procedures, there is still Page: 489-492, Paper no. 195, Paper Code: OT15 significant swirl left in the flow. The measurements thus point to Abstract: The behaviour of the wake Strouhal number for flow ways for improving their design. In addition, the paper describes past a cylinder close to a free surface at low Froude numbers is the experimental facility and methods used. The experimental re- investigated numerically. The results obtained are compared with sults would also be useful as test cases for comparison with nu- those for flow past a cylinder close to an adjacent no-slip bound- merical simulations. ary. Favorable agreement is obtained despite the large differences Analysis of Four Data Reduction Schemes Applied in Reynolds number. As the distance between the wall and the to Four-sensor Hot-wire Probes cylinder is reduced the Strouhal number, as measured from the P. Lavoie, A. Pollard time varying lift, increases to a maximum at a gap ratio of 0.70, Page: 509-512, Paper no. 134, Paper Code: ET04 before decreasing rapidly with shedding finally ceasing altogether Abstract: Four data reduction schemes for four-sensor hot-wire at gap ratios below 0.16. The agreement between the results for a probes have been implemented and used to measure the turbu- free surface and a no-slip boundary indicates that the mechanism lent statistics in the near field of a round jet. Each data reduction behind the suppression of vortex shedding is common. scheme was used on the set of signals obtained and compared to data from the literature and LES computation to quantify the level of accuracy of the probe and the data reduction schemes proposed in the literature in a consistent manner. Results for ur ms, u v and v w are presented.
15 An Investigation on the Length to Diameter Ratio of Characterisation of the Plug-Holing Phenomenon for Hot Wire Filament in Turbulence Measurements the Exhausting of a Low Density Gas Layer J.D. Li J. Viot, O. Vauquelin, N. Rhodes Page: 513-516, Paper no. 138, Paper Code: ET05 Page: 529-532, Paper no. 246, Paper Code: ET09 Abstract: Heat generation and transfer along hot wire filament and Abstract: This paper presents some results of a study carried out its supports are analyzed numerically. From this analysis, it is in order to quantify the critical condition associated with the plug- shown that the ratio between the heat conduction and heat con- holing phenomenon. The plug-holing is defined when a dip ap- vection depends on the length to diameter ratio of the hot wire, pears on the free surface of a fluid draining from a container. Ex- the length of the wire support, the types of wire material and the periments and numerical simulation were carried out for different Reynolds number based on the wire diameter. By keeping this ratio values of the basic parameters of the problem : the initial height to a constant, a formula based on correlating the numerical data is and the density of the drained fluid, the size and the shape of the given to determine the optimum length to diameter ratio for given vent for draining. A theoretical model is proposed and compared Reynolds number and hot wires. with experimental and numerical data. Measuring Local Time-Averaged Airflow Velocity Transverse Velocity and Temperature Derivative Through an Automotive Heat Exchanger Measurements in Grid Turbulence Eton Y. Ng, Simon Watkins, Peter W. Johnson, Lindsay T. Zhou, R.A. Antonia, J-J. Lasserre, M. Coantic, F. Mole Anselmet Page: 517-520, Paper no. 164, Paper Code: ET06 Page: 533-536, Paper no. 267, Paper Code: ET10 Abstract: In some applications, the airflow in an air-cooled cross- Abstract: The same probe, comprising two parallel wires, is used flow compact heat exchanger is complex and non-uniformly dis- to measure either velocity or temperature derivatives in shearless tributed. The present study reveals the considerable lack of uni- grid turbulence. The aerodynamic interference of the probe affects formity across the radiator air face for typical automobiles. This the mean velocity when the transverse separation ∆y between the paper presents the development of an experimental technique for wires is smaller than about 3η, where η (≈0.4 mm) is the Kol- measuring the local time-averaged airflow velocity through radia- mogorov length scale, but does not affect the mean temperature. tors. Test results using a full-scale vehicle tested in a wind tunnel Moments of transverse velocity and temperature derivatives are are presented, including flow visualisation around the radiator and significantly but similarly affected when ∆y<3η, thus suggest- contour plots of the velocity distribution over the radiator core. ing that this effect is more likely to be caused by electronic noise A Single Moduled Laser Interferometer for Wall than aerodynamic interference. After noise corrections are ap- Shear Stress Measurement plied, the resulting derivative variances are brought into alignment N. Nishizawa, M.B. Jones, M.S. Chong with values inferred from two-point correlations with respect to y. Transverse derivative variances and their corresponding spec- Page: 521-524, Paper no. 166, Paper Code: ET07 tra satisfy isotropy closely but second-order structure functions Abstract: A Laser Interferometer Skin Friction meter (LISF) has satisfy it only when the separation is less than about 10η. been designed and developed for the wall shear stress measure- ment. Since its introduction in the mid 1970s, the Laser Inter- Performance of an Energy - Temperature Dissipa- ferometer has been the focus of a number of studies, however, a tion Rate Probe in Decaying Grid Turbulence number of its major disadvantages have been left unsolved. Con- T. Zhou, R.A. Antonia, L.P. Chua ventional LISF and FISF (Fringe Imaging Skin Friction meter) require Page: 537-540, Paper no. 268, Paper Code: ET11 silicone oil to be applied while there is no airflow. This restriction Abstract: Instantaneous energy and temperature dissipation rates has created problems in the application and accuracy of the Inter- are measured simultaneously in decaying grid turbulence using a ferometry system. probe consisting of 4 X-wires (a total of 8 hot wires operated in As a solution to this problem, a single moduled and single beam In- constant temperature mode) and 2 pairs of parallel cold wires (op- terferometer was designed and built. The original concept of single erated in constant current mode). The directly measured mean val- module design was established by Seto & Hornung [8], and devel- ues of the energy and temperature dissipation rates agree, within ± oped by Nishizawa et al.[4]. The major change from the previous 10%, with those obtained from the decay rates of the mean tur- design was an introduction of a built-in oil injector which enables bulent energy and temperature variance. The probe also yields all silicon oil to be deposited upon the surface when a boundary layer three fluctuating vorticity components; after correction for spa- is present. Preliminary wall shear stress measurements showed tial resolution, their spectra are in close agreement with isotropic good agreement with the data from the Clauser chart and Preston calculations over nearly all wavenumbers. The vorticity variance tube methods. The device was also applied to high Reynolds num- decays with the same power-law behaviour as the mean energy dis- ber turbulent boundary layers as a method which is independent sipation rate. Transport equations for the mean energy and tem- ± of the law of the wall in determining the wall shear stress. perature dissipation rates are satisfied, within 10%, by the data obtained from this probe. Manipulation of Natural Frequency Separation to Im- prove Dynamic Response of Hot-Wire Probes Rapid Measurement of Bubble Size in Gas-Liquid Flows Using a Bubble Detection Technique C.S. Anderson, S. Eren Semercigil, Özden F. Turan Yonggang Zhu, Jie Wu, Richard Manasseh Page: 525-528, Paper no. 208, Paper Code: ET08 Page: 541-544, Paper no. 270, Paper Code: ET12 Abstract: The slender sensing wire of a hot-wire probe can res- Abstract: A bubble detection technique has been developed for onate with large amplitudes in turbulent flow. This resonance can fast and accurate measurement of bubble size distributions in gas- cause measurement inaccuracies since the wire is no longer sta- liquid two-phase systems. The technique uses advanced digital im- tionary with respect to the flow. Once the wire begins to oscillate, age processing which consists of edge detection and bubble edge any measurement taken is a combination of the flow velocity and recognition. A borescope and a high-resolution CCD camera are the wire velocity, and for this reason, the resulting measurements used to capture the images of bubbles. The accuracy of the tech- can be inaccurate. Here, selected experimental results are shown nique is tested in a controlled bubble generation device. Measure- which identify this inaccuracy. ments are also carried out in mixing vessels to study the effect of The authors have previously investigated structural modifications impeller speed and gas sparging rate on the bubble size and its dis- to the profile of the sensing wire to reduce large amplitude oscil- tributions. It has been found that the present technique can mea- lations. They have shown that geometries having close first and sure bubble size with very good accuracy. The bubble sizes mea- second natural frequencies have favorable vibration characteris- sured in the mixing vessels agree well with other techniques. The tics. Structural modifications to the wire geometry are suggested dependence of bubble size distribution on impeller speed, tank to reduce these inaccuracies. Experimental results are presented size and sparging rate is also quantified from the present tech- here supporting the new geometries. nique and provides justification for the technique.
16 Gas Dynamics is the unyielding boundary conditions that prevail beyond regular reflection which force this remarkable deviation from the classical Natural Ventilation by the Competing Effects of Lo- shock wave theory to take place. calised & Distributed Heat Sources Gary R. Hunt, Joanne M. Holford, Paul F. Linden Shape Optimisation for Supersonic Nozzle Flows Page: 545-548, Paper no. 99, Paper Code: GD01 D.H. Smith Page: 565-568, Paper no. 219, Paper Code: GD06 Abstract: We consider the steady natural ventilation of an enclo- sure with openings at high and low level, heated uniformly by the Abstract: Constrained minimisation of the pressure integral in combination of a distributed source occupying the entire floor area quasi one-dimensional nozzles is studied for supersonic inlet and and, simultaneously, by a localised heat source at the centre of the subsonic exit conditions via active set methods with polynomial floor. The stratification and flow patterns produced by the com- shape functions. Optimal configurations are generated and dis- bined heat sources were examined in a series of experiments using cussed in terms of geometry, shock location, constraints, bound- a small-scale model to represent a generic single-spaced room or ary conditions and nonuniqueness. building. We present results from these experiments which show Groundwater that the general two-layer stratification and displacement flow pro- duced by a localised source in isolation is maintained when the Assessing the Accuracy of a Finite Element Code in localised heat flux is greater than approximately one sixth of the Solving the Advection-Diffusion Equation Using the distributed heat flux. For weaker localised sources a well-mixed Gauss Pulse Test interior is established. A.G. Smith, M.D. Teubner Effect of Column Spacing on Wave Force Page: 569-572, Paper no. 220, Paper Code: GW01 C.E. Quadros Abstract: Using the Galerkin Finite Element Technique, a numer- Page: 549-552, Paper no. 189, Paper Code: GD02 ical code to study groundwater systems is being developed. This Abstract: The study is of an offshore structure consisting of slen- code has been applied to the Gauss Pulse Test to determine the der columns near the free surface and large buoyancy pontoons accuracy of a number of solution schemes: in particular, which near the base that is moored to the sea bottom like a Tension Leg value of theta in the numerical time step theta algorithm gives the Platform. The effect of the spacing between the columns of the most accurate solution of the two-dimensional advection- diffu- structure on the horizontal component of the total wave force due sion equation. The theta algorithm enables time stepping to be to an irregular wave has been investigated. Since the columns are performed explicitly (θ = 0), implicitly (θ = 1) and any combina- slender, diffraction of the incident wave field has been neglected tion thereof (0 <θ<1). and the wave force has been computed using a method proposed Whilst the Gauss pulse test is a benchmark problem for assess- by Borgman for an irregular wave. This research has been done ing advection-diffusion type equations, it has predominantly been to get an insight into the design of an offshore structure that will used to assess finite difference methods. Here however, it is used experience low horizontal force in the west coast of India where to evaluate a finite element scheme. A brief overview of the code the use of this structure is contemplated. is given, and various results for the Gauss pulse test discussed. Effect of Unequal Granular Temperature on Number of Collision and Dilute Viscosity of Kinetic Theory Hydraulics M.F. Rahaman, Jamal Naser Supercritical Leaps in Two-Layer Hydraulics Page: 553-556, Paper no. 191, Paper Code: GD03 S.R. Clarke, E.R. Johnson Abstract: Kinetic theory for particles of the same mass and the Page: 573-576, Paper no. 46, Paper Code: HL01 same granular temperature is well established. However, kinetic Abstract: The finite-amplitude flow past topography of a two-layer theory for particles of different mass and different granular tem- fluid is considered. Assuming that the topography and waves are perature is yet to be established. In this paper we re-derived the long compared to the channel depth a pair of finite-amplitude equations of the number of collisions and dilute viscosity for a bi- equations can be derived which describes the evolution of the flow nary granular mixture with unequal granular temperature. Here from a given initial state. At leading order these are the classi- particles are taken as of different size and density. The results cal unsteady hydraulic equations for two-layer flow; at next order indicate significant discrepancies when compared with the theory dispersion appears. With the inclusion of dispersion new types that is derived by assuming particles of equal mass and equal gran- of hydraulic solutions involving rapid transitions between super- ular temperature. critical branches can be investigated. Spectrally accurate unsteady Optically Addressed Pressure Sensors for Transient integrations of the evolution equations show that these solutions Gas Dynamics: Calibration of a Preliminary Design involving ’supercritical leaps’ can be expected to evolve from real- S.A. Sharifian, D.R. Buttsworth istic initial conditions. Page: 557-560, Paper no. 212, Paper Code: GD04 Investigation of Spillway Behaviour Under In- Abstract: The design of pressure sensors based on interferometric creased Maximum Flood by Computational Fluid Dy- measurements of diaphragm deflection for transient gas dynam- namics Technique ics experiments is discussed. Quasi-steady calibration results from D.K.H. Ho, K.M. Boyes , S.M. Donohoo one such sensor are presented. Results from a dynamic calibration Page: 577-580, Paper no. 91, Paper Code: HL02 of the same sensor are also described. Predictions of diaphragm Abstract: Early dam structures were designed and built with lim- behaviour based on a clamped circular diaphragm model are within ited hydrological information. As such many existing spillway about 30% of the results obtained from the static and dynamic cal- structures are under-sized to cope with the revised probable max- ibrations. However, a strong temperature sensitivity is also appar- imum flood levels. Potential problems such as the generation of ent. Future development will focus on reducing the temperature lifting pressure and cavitation over spillway crest under flood con- sensitivity of the sensor in transient applications. dition will be encountered. Historically, scaled physical models Outline of a Theory of Non-Rankine-Hugoniot Shock have been constructed in hydraulic laboratories to study these be- Wave in Weak Mach Reflection haviours, but they are expensive, time-consuming and there are Alfred Siegenthaler, Jehangir T. Madhani many difficulties associated with scaling effects. Today, with the advance in computer technology and more efficient computational Page: 561-564, Paper no. 217, Paper Code: GD05 fluid dynamics (CFD) codes, the behaviour of hydraulic structures Abstract: At the previous AFMC, the background for expecting can be investigated numerically in reasonable time and expense. a departure from Rankine-Hugoniot theory at the base of the re- This paper describes the CFD modelling of spillway behaviour un- flected shock wave in weak Mach reflection was exposed. The re- der rising flood levels two- and three-dimensionally. The results sults of some pertinent experiments performed in the supersonic have been validated against published data and good agreement wind tunnel were then presented. They confirmed the hypothe- was obtained. The same technique was applied to investigate a sised irregular behaviour. In the present contribution, the elabo- spillway structure on the largest concrete gravity dam in Australia. ration of a theory of transgressed shock wave properties is pre- sented. This concept enables to calculate the modified jump pro- cess. It fully accounts for the known experimental observations. It
17 Hydrodynamics On Competition Between Modes at the Onset of Thermocapillary Convection Under a Uniform Ver- Effect of Double Diffusion on Mixing of Discharges tical Magnetic Field from Coastal Outfalls I. Hashim, N.M. Arifin M.M. Chow, S.S.S. Cardoso, Joanne M. Holford Page: 597-600, Paper no. 87, Paper Code: HD05 Page: 581-584, Paper no. 38, Paper Code: HD01 Abstract: The stability of oscillatory thermocapillary (Marangoni) Abstract: The discharge of an axisymmetric buoyant jet of less convection of electrically conducting fluid layers heated from be- salty and colder wastewater into an unstratified stagnant sea leads low under the influence of a uniform vertical magnetic field is in- to the formation of a cloud of pollutant at the sea surface. We vestigated numerically using linear stability theory. In particular consider the transport of pollutants arising from double diffu- we present an example of a situation in which there is competition sion at the lower interface of this cloud; this phenomenon has not between modes at the onset of convection when the layer is heated been considered in conventional models hitherto [1]. Conserva- from below. tion equations are solved numerically to obtain the temperature, Structure of Vortex Breakdown in a Torsionally salt and pollutant concentration profiles in the buoyant jet, cloud Driven Cylinder at Low Reynolds Number and surrounding sea water. Two outfall scenarios corresponding K. Hourigan, M.C. Thompson to low and high interface stability are considered. The interaction Page: 601-604, Paper no. 97, Paper Code: HD06 between double diffusion and buoyant jet entrainment results in the recirculation and accumulation of pollutant. When the inter- Abstract: Flow visualisation using tracer and particle techniques face stability is low, the pollutant concentration doubles near the is well known to be susceptible to fallacious interpretation for un- buoyant jet, in the timescale required for the polluted cloud to steady shear flows. Recent experimental observations using these reach the coast. The effect of double diffusion on pollutant trans- types of techniques have led to the conclusion that even for low port in the high stability case is found to be small. Reynolds number flows, the vortex breakdown bubble in a torsion- ally driven cylinder is not closed and has an inflow/outflow asym- Breakdown of Inertial Waves in a Tube with Variable metry at its tail. These results would suggest that this type of Cross-Section vortex structure is more similar to that observed in the open vor- O.G. Derzho, R. Grimshaw tex tube than previously thought and is therefore a "true" vortex Page: 585-588, Paper no. 58, Paper Code: HD02 breakdown. In this article, an alternative explanation of the ob- Abstract: In this study we describe a theoretical asymptotic model served asymmetry is offered. It is demonstrated that the dye visu- for large amplitude stationary inertial waves in an axially symmet- alisation technique can lead to spurious interpretations even for a ric swirling flow of an ideal fluid in a circular tube with variable steady axisymmetric flow field, due to tracer diffusion and minute cross-section. Calculations are presented for the special, but im- errors in tracer injection location. It is concluded that there is no portant case when the upstream flow is uniform and always super- evidence that bubble structure in a confined cylinder flow is asym- critical. We find that the breakdown of inertial waves in divergent metric at these lower Reynolds number. tubes is extremely sensitive to the variations of the cross-section. Prediction of Yacht Roll Motion at Zero Forward The breakdown bubble is generally asymmetric and it may turn Speed into the diverging tail, especially in a convergent part of the tube. K. Klaka, J.R. Krokstad, M.R. Renilson Possible relevance of the calculated structures to the experimen- Page: 605-608, Paper no. 124, Paper Code: HD07 tally observed types of the breakdown is discussed. Abstract: The roll motion of a yacht at zero Froude number is being Inertial Oscillations and the Thermal Bar investigated, motivated by limitations of existing theoretical mod- D.E. Farrow els of roll motion when applied to bodies with large appendages. Page: 589-592, Paper no. 72, Paper Code: HD03 A time domain single degree of freedom roll model has been de- Abstract: Small bottom slope, inviscid solutions are found for a veloped in order to identify the dominant excitation and damp- model of the thermal bar system. The model includes Coriolis ef- ing sources. The canoe body forces were determined from a wave fects and variable heat input. The solutions include inertial oscil- diffraction program whilst the appendages were treated as fully lations that have a significant effect on the circulation, especially submerged flat plates. Calculation of the forces acting was based for the case when the heating is instantaneously applied. on a stripwise Morison formulation. A series of full scale valida- tion experiments has also been conducted, in calm water and in Flow Over a Body of Revolution in a Steady Turn ocean waves. P.A. Gregory, P.N. Joubert, M.S. Chong Page: 593-596, Paper no. 79, Paper Code: HD04 The results show that the keel, rudder and sail dominate the damp- ing, whilst the canoe body contributes very little. The hydrody- Abstract: While the mechanisms of flow separation for a subma- namic damping was non-linear with respect to wave amplitude, rine in steady rectilinear flow are well understood, the flow sepa- but the overall damping with a sail hoisted is only weakly non- ration behaviour of a submarine during a manoeuvre is not as well linear with respect to wave amplitude because the sail dominates understood. The importance of this has lead us to investigate the the damping, particularly in a wind field. The numerical model flow separation over a submarine-like body of revolution in a turn predicts a strong influence of wave heading which is not borne out of fixed radius. by the full scale trials. The flow separation over the manoeuvring body is examined by A Study of a Backward Facing Step Flow at Two using a deformed body placed in rectilinear flow to simulate the Reynolds Numbers flowfield created by a body moving through a circular path. This J. Kostas, J. Soria, M.S. Chong method was used by Von Karman at the Guggenheim Airship Lab- Page: 609-612, Paper no. 128, Paper Code: HD08 oratory and by Gurzhienko in Moscow in the 1930’s to investigate the manoeuvring of airships. Abstract: Particle image velocimetry measurements were carried out on a backward facing step flow at Reynolds numbers of Reh = The deformed model is constructed such that the local angle of at- U∞h/ν = 580 and Reh = 4660 (based on step height and freestream tack is the same for a regular model placed in curved streamlines. velocity). Data in the x − y and x − z planes was acquired and is Velocity should be varied linearly across the test section to ensure be presented. the local velocities at the deformed model surface are equal to the velocity along the manoeuvring model. The distribution of in-plane Reynolds stresses and turbulent ki- netic energy production is significantly different between Reynolds Numerical simulations conducted using the CFD code FLUENT show numbers. The peaks in the Reynolds stress and kinetic energy pro- the validity of this transformation. Results for a body placed in a duction distributions are shifted further downstream for the low rotating reference frame are compared to a deformed body in rec- Reynolds number flow. This behaviour is primarily due to the dif- tilinear flow. ferent streamwise locations at which vortical interactions occur in each flow case. The relationship between the instantaneous flow structure and the mean turbulence quantities is also discussed.
18 Water Column Destratification Using a Pulsed Jet Wave Forces on a Body in Confined Waters System J. Xia, J.R. Krokstad C.J. Lemckert, C. Forsyth Page: 629-632, Paper no. 259, Paper Code: HD13 Page: 613-616, Paper no. 136, Paper Code: HD09 Abstract: In this paper, we study the interaction of gravitational Abstract: The efficiency at which drinking water reservoirs can be water waves with stationary ocean structures near a vertical bound- artificially destratified by mechanical or pneumatic pumping sys- ary or in a wave channel. The water depth is assumed finite imply- tems depends upon numerous factors, including the rate at which ing that the interference effect of not only the vertical boundaries water is pumped from one vertical level to another. To date, no but also the horizontal bottom is considered. Presented here are studies have been cited that examine whether it is possible to en- a potential flow theory and the boundary-element method (BEM) hance destratification efficiency by using a pulsed flow instead of a towards solving this problem. The numerical results include 1st- continuous one in order to determine whether a pulsed flow could and 2nd- order wave exciting forces of a hemisphere, and are com- enhance mixing rates, a set of detailed laboratory experiments was pared with available computations and published model test re- undertaken using a vertical positively-buoyant jet mixing system sults. The theoretical findings based on a parametric study in this to destratify a two-layer stably-stratified water column. The puls- paper are associated with practical design considerations for a pro- ing flow considered had a continual -on-off- cycle with the on- and posed deepwater ocean basin to be built at Jervoise Bay, Western off- times kept constant within any one experiment, but varied be- Australia. tween different experiments. The results showed that when the Experimental Observations of Rayleigh-Taylor In- on-flow time was short and the off-flow time relatively long the stability in a Shock Tube leading vortex that formed at the initiation of the on-flow signifi- Xiao-Liang Wang, Motoyuki Itoh cantly reduced the mixing rates, and hence the efficiency. Page: 633-636, Paper no. 261, Paper Code: HD14 An Experimental and Numerical Investigation of Abstract: Rayleigh-Taylor instability in a shock tube has been in- Taylor Vortex Flow in the System of Coaxial Rotat- vestigated experimentally. Such instability was produced by accel- ing Conical Cylinders erating a liquid column down a vertical circular tube employing M.N. Noui-Mehidi, N. Ohmura, K. Kataoka shock wave impact. The liquid column is a combination of decane Page: 617-620, Paper no. 167, Paper Code: HD10 and salt solution. Acceleration of about 26 times gravitational ac- Abstract: In the present work both experimental and numerical in- celeration with decane depth of 150 mm and salt solution depth of vestigations are combined for the study of Taylor Vortex Flow (TVF) 100 mm were studied. The resulting instability of the gas/liquid between coaxial conical cylinders with the inner one rotating and (air and decane) interface and the liquid/liquid (decane and salt the outer one at rest. The numerical simulations are conducted by water) interface was recorded and later analysed using high-speed the use of a finite difference method applied to the SMAC formu- video images. Cavity formation was observed in the middle of the lation. These simulations permitted the study of the apex angle gas/liquid interface soon after the shock wave impact; bubbles and effect on the development of Taylor vortices. In the steady TVF spikes then developed across the rest of the interfacial plane. Mea- three modes of six, seven and eight pairs of steady Taylor vortices surements showed that the growth coefficient of the cavity is about are observed when the inner conical cylinder rotation is acceler- twice of that of the bubbles. The growth coefficient of the bubbles ated linearly with different acceleration rates β. The experimental is nearly independent of the Atwood number, while the growth co- results involve flow visualization and an electrochemical method efficient of spikes is sensitive to the Atwood number. (polarography) for investigating the time dependency of the flow Hydrodynamic Performance of a Vortex Generator structures. P.A. Brandner, G.J. Walker Internal-Wave Radiation From an Oscillatory Source Page: 637-640, Paper no. 274, Paper Code: HD15 in a Depth-Dependent Medium Abstract: The performance of a vortex generator intended for a Dave Broutman, James W. Rottman marine application is investigated experimentally in a cavitation Page: 621-624, Paper no. 200, Paper Code: HD11 tunnel. Several tests were made as a preliminary study to gain Abstract: We develop a method for analysing linear internal waves basic knowledge of an initial design concept. Investigations in- generated by an oscillating obstacle moving horizontally at con- cluded flow visualisation of local flow and wake trajectory, cavi- stant speed through a depth-dependent medium. The new feature tation inception and occurrence, and measurement of boundary of the method is that it uses ray theory not to approximate the layer profiles both upstream and downstream of the vortex gener- wavefield directly (which would fail near the source and near caus- ator. Boundary layers were measured in the non-cavitating condi- tics) but to approximate the normal modes. The normal modes tion only. Two upstream boundary layer profiles were tested and are then combined by inverse Fourier transform to obtain a spa- were found to have little influence on cavitation inception for a tial description of the wavefield. We discuss this method and its range of incidence. relation to the theory of Lighthill [5]. We illustrate the method by Numerical Study on the Dynamics of a Cavitation computing lee waves radiated from a sphere in a cross flow with Bubble Near a Rigid Body vertical shear. M.T. Shervani-Tabar, Kh. Arshadi Transient Mixing Events in Stably Stratified Turbu- Page: 641-644, Paper no. 278, Paper Code: HD16 lence D.D. Stretch, J.W. Rottman, K.K. Nomura, S.K. Venayag- Abstract: Cavitation damage in structures is of universal interest amoorthy and concern. Cavitation bubbles are produced in liquid flows when the liquid pressure drops below the saturated vapour pressure. Page: 625-628, Paper no. 231, Paper Code: HD12 These bubbles flow with liquid and collapse in the high pressure Abstract: Mixing efficiency in stratified flows is the proportion of region, The collapse of a cavitation bubble in the vicinity of a rigid turbulent kinetic energy that goes into increasing the potential en- boundary is accompanied by a high velocity liquid jet. The liquid ergy of the fluid by irreversible mixing. In this research direct jet, in the absence of buoyancy forces, forms on the side of the numerical simulations (DNS) of transient, homogeneous, stably- bubble far from the rigid boundary and is directed towards it. The stratified turbulence are used to determine the mixing efficiency impingment of the liquid jet to the rigid boundary is believed to be as a function of the stratification. The DNS results are compared one of the important factors of cavitation damage. In this paper with data from grid experiments. There is qualitative agreement dynamics of a cavitation bubble near a rigid body is studied using between the DNS results and the experimental data, but significant the Boundary Element Method. quantitative discrepancies. The grid turbulence experiments sug- Numerical study of growth and collapse of a cavitation bubble near gest a maximum mixing efficiency of about 6%, while DNS gives a rigid body gives detailed information about the migration of the about 30%. We conclude that the main source of the disagreement bubble away or towards the rigid body, the volume change of the is the inaccuracy in determining the initial turbulence energy input bubble during its growth and collapse and the formation of the in the grid turbulence experiments. liquid jet. Development and direction of the liquid jet is studied in different cases.
19 Industrial Flows well with induced pressure gradients. Numerical Simulation of Abrasive Water Jet for Dif- Comparative Study of Flow in a Mixing Vessel ferent Taper Inlet Angles Stirred by a Solid Disk and a Four Bladed Impeller Dewan H. Ahmed, Elias Siores, Jamal Naser, Frank L. L. Mununga, K. Hourigan, M.C. Thompson Chen Page: 661-664, Paper no. 161, Paper Code: IF05 Page: 645-648, Paper no. 2, Paper Code: IF01 Abstract: Laminar flow in an unbaffled mixing vessel stirred by Abstract: Abrasive water jet uses for precision cutting in mod- a solid disk rotor and a 4-blade impeller was simulated using the ern technology. A Computational Fluid Dynamics (CFD) method CFD software package FLUENT. The computational geometries and has been developed to find out the particle, water and air velocity grids were generated using a pre-processor software package (Gam- distributions for abrasive water jet. The study has been carried bit) and then exported to Fluent where the rotating reference frame out using a multi-phase approach. The granular abrasive particles approach was employed to predict the flow field. The flow field is were treated a continuous phase. The air used for pumping the characterised by two recirculation regions, the centre of which was abrasive particles into the jet device was treated as a continuous investigated. The swirl velocity and the Z-vorticity at the recircula- phase and the water was treated as the principal continuous phase. tion centre are much higher for the 4- blade impeller than for the The governing equations were discretized using the finite volume solid disk rotor. Simulated results also show that both the swirl approach. The solutions were obtained using the Inter-Phase Slip velocity and the Z-vorticity are higher near the impeller. Results Re Algorithm (IPSA). The governing equations were closed using the show that at Reynolds number ( ) = 200 the 4-blade impeller ex- k-e turbulence model. As the jet velocity depends on the acceler- hibits a sharp increase in the swirl velocity near the axis at the ation process of water and abrasive particles, the simulation was bottom of the mixing vessel, which generates an upwards vortical performed using different taper inlet angles. It was found from flow. The results show that the solid disk rotor may be viable for the simulations that the acceleration process was much better for smooth laminar applications. higher taper inlet angle leading to the maximum velocity of the jet Using Free and Restricted Sloshing Waves for Con- at the exit of the focus tube. The velocities and volume fractions trol of Structural Oscillations of air, water and abrasive particles at the exit were compared with Tam D. Truong, S. Eren Semercigil, Özden F. Turan the available experimental data. The simulated results showed rea- Page: 665-668, Paper no. 209, Paper Code: IF06 sonably good agreement with the experimental data. Abstract: Sloshing is the large amplitude and low frequency oscil- Plumes Driven by Free-Falling Streams of Solid Par- lation of a liquid in a partially filled container. It is normally de- ticles sired to suppress sloshing to prevent its detrimental effects on the Paul Cooper, Zeqin Liu, Peter W. Wypych safety of its container. Alternatively, intentionally induced slosh- Page: 649-652, Paper no. 50, Paper Code: IF02 ing may be used to passively control structural vibrations. The Abstract: There are many situations where a granular bulk solid use of sloshing as a structural controller is similar to the use of a undergoes free-fall through a quiescent ambient fluid. Important classical tuned vibration absorber. The advantage of the sloshing practical examples include the filling of bins, the transferring of absorber over the tuned absorber is its simplicity, especially for material from belt to belt or the building of a stockpile of raw ma- cases where a liquid container has to be accommodated as part of terial, such as iron ore or coal, by dropping new material on to the a structure such as a water tower. top of the stockpile from a conveyor belt. This paper details ex- This paper summarises the results of an extensive experimental perimental research into this fundamental problem, focussing in study on the effectiveness of a sloshing container as a vibration particular on the volume flow rate of air induced/entrained by the controller. Water, a light mineral oil and mineral oil suspension, falling stream of solid material. Experimental results are presented were used as sloshing liquids. The container geometries allowed for the free-fall of a bulk solid material (alumina) through air. The either a free sloshing wave or a restricted wave with a cap located functional dependence of the induced air flow rate and the velocity at varying distances from the free surface. Results demonstrate profile on process parameters such as drop height and bulk mate- the parameters required for optimal structural control. rial mass flow rate is investigated. Comparisons are made to other Sloshing Control with Container Flexibility forms of jets and plumes, including the classical miscible plume model and bubble plumes. One of the major findings is the fact M. Gradinscak, S. Eren Semercigil, Özden F. Turan that the angle of spread of the particle-driven plume is much less Page: 669-672, Paper no. 210, Paper Code: IF07 than for the other entrainment flows. Abstract: Sloshing is the low frequency oscillation of a liquid in a A 3D Navier-Stokes Solver for the Design and Anal- container. In transportation, sloshing of liquid cargo may cause ysis of Turbomachinery dynamic instability of the vehicle. Sensitive liquid cargo such as I. Huntsman, R. Hothersall suspension type of foodstuff may spoil during transport due to Page: 653-656, Paper no. 100, Paper Code: IF03 sloshing. If not controlled effectively, sloshing of liquids in storage tanks may lead to large dynamic stress to cause structural failure. Abstract: This paper presents the computational fluid dynamics Hence, the study of sloshing and measures to suppress it are well (CFD) software developed at the University of Canterbury in con- justified. junction with Hamilton Jet for the design of water jet impeller and stator components. The 3D software solves the Reynolds averaged Although numerous studies have been reported in the literature, Navier-Stokes equations on a finite volume "H" mesh. A second or- attempts to control sloshing have been relatively limited. Amongst der upwind differencing scheme is used for the inviscid fluxes and these limited control attempts, no effort has been reported to em- the Baldwin-Lomax turbulence model is incorporated. A signifi- ploy the flexibility of the liquid containers to suppress sloshing. cant amount of research involved the validation of this software This paper outlines the results of an extensive numerical study to through experimental testing. Rotating and stationary blades of determine important parameters of a flexible liquid container for varying blade geometry, hub/casing ratio and profile were tested. suppressing the sloshing of its content. The results of some of these tests are compared with the numeri- A Flow Visualization Study on the Movements of cal predictions of the 3D program and are presented in this paper. Solid Particles Propelled by a Collapsing Cavitation Influence of Temperature Boundary Conditions in Bubble the Wire-Coating Process W.K. Soh, B. Willis B.P. Huynh Page: 673-676, Paper no. 221, Paper Code: IF08 Page: 657-660, Paper no. 103, Paper Code: IF04 Abstract: The aim of this work is an examination of bubble-particle Abstract: Influence of temperature boundary conditions on the interaction near a solid boundary in an effort to determine why the flow field inside the die of the wire-coating process is investigated addition of particulate to a cavitating flow produces damage that numerically, using viscous fluids of a Newtonian type for coating far exceeds that expected by the summation of the cavitation and material and a finite element method. It is found that changing particulate effects acting independently. the die or wire temperature can have significant effects on the flow High-speed flow visualization technique is applied to the study velocity, and hence flow rate. On the other hand, the heat trans- of the movements of solid particles induced by the collapse of fer coefficient between the coat’s free surface and its surroundings cavitation bubble. The captured images of the particles and the has only negligible influence. Also, flow rate variation correlates cavitation bubble are analysed to provide trajectories and velocity
20 vectors of the particles. The phenomenon points to a possible ex- element code developed by the first author. Whilst this is primarily planation on the mechanism of cavitation-particulate erosion on a fundamental study, the flow system represents a subcomponent solid surfaces. of fluid-particle flows and is of importance to the development of Computing Flow in a Spiral Particle Separator physical models describing flows with non-zero particle loadings. Y.M. Stokes Page: 677-680, Paper no. 228, Paper Code: IF09 Experimental flow visualisations reveal that the wakes interact str- Abstract: To achieve improvements in the design of spiral particle ongly at small separations and at least three different wake states separators, used in the mineral processing industry, it is necessary can be observed. The numerical results reported here were aimed to have a good understanding of the fluid flow in them and the fac- at accurately simulating the change in the wake state as the sep- tors that affect it. To this end, we are developing computational aration is decreased. The results are analysed in terms of vor- techniques for determining the flow in a spiral channel of general ticity generation and interaction, and flow-induced forces on the geometry, including the complex free-surface shape. These can spheres. then be used to investigate how the flow, and ultimately separa- On the Mechanisms of Wake-Body Interactions in a tion, is affected by geometrical parameters and fluid flow proper- Tandem Array of Two Square Cylinders ties. K.L. Lai, M.K. Bull Continuous Rheometry for Industrial Slurries Page: 697-700, Paper no. 24, Paper Code: JW04 T.J. Akroyd, Q.D. Nguyen Abstract: Numerical simulations, by discrete vortex methods, of Page: 681-684, Paper no. 275, Paper Code: IF10 the flow over a tandem array of two square cylinders when a vor- Abstract: Mineral solids are usually processed, produced or han- tex street is formed within the gap are presented. Attention is dled in the form of two-phase slurries. Examples may be found in concentrated on the interaction between these vortices and the all aspects of mining and mineral processing. The ability to han- downstream cylinder. dle and process mineral slurries depends on the flow behaviour The simulations show that the gap vortices, impinging on the blunt of the slurries. A good knowledge of the flow characteristics of leading edge of the downstream cylinder, undergo distortion and these slurries is very important in the design and optimisation of clipping. The minor part of a clipped vortex combines with a sep- mining and extractive processes. It is essential that the rheological aration bubble on a side face of the cylinder to form a secondary properties of these slurries be determined as accurately as possi- vortex. This vortex, the major part of the clipped vortex, and a ble. This however, is not an easy task when dealing with hetero- further vortex formed by flow separation from the trailing edge geneous suspensions where there are large and high-density solid of the downstream cylinder are shed, essentially simultaneously, particles. Accurate and reliable measurements of the rheological into the wake; they merge to form one of the vortices in the final properties of these slurries using conventional viscometric instru- Karman street downstream of the array. The impingement process ments can be difficult, if not impossible, since the solid particles couples vortex shedding from the upstream and downstream cylin- settle rapidly under the influence of gravity. We report on the de- ders, with a phase difference varying linearly with gap width. The velopment of an on-line helical flow rheometer for characterising calculated fine detail of vortex impingement on the downstream the rheological behaviour of settling mineral slurries. The instru- cylinder complements flow-visualisation experiments by other in- ment design is based on the principles of helical flow, which is the vestigators. combination of tangential Couette and axial annular flows. The data reduction procedure developed is firmly based on the theory A Comparison of Forced and Freely Oscillating of helical flow and has been extensively tested and validated with Cylinders model fluids of different rheological behaviour. Testing of the he- J. Carberry, J. Sheridan, D. Rockwell lical flow rheometer and the data reduction method with various Page: 701-704, Paper no. 26, Paper Code: JW05 solutions, including Newtonian and pseudo-plastic fluids have pro- Abstract: The fluid-structure interactions between an oscillating duced good results. cylinder and the natural instability of the wake have been studied by simultaneously measuring the structure of the near wake and Jets and Wakes the forces on the cylinder. In this paper we examine the results of Energy Harvesting Eel externally forced sinusoidal oscillations and compare them with J.J. Allen, A.H. Techet, R.M. Kelso, A.J. Smits the vortex induced oscillations of an elastically mounted cylinder. While wake structure and the variation of the vortex lift phase show Page: 685-688, Paper no. 4, Paper Code: JW01 some remarkable similarities, the results of these, and previous Abstract: Experiments were performed to investigate the possibil- investigations, show that the forced oscillations can result in neg- ity of using flexible piezoelectric membranes as power generation ative energy transfer for purely sinusoidal motion at frequencies devices in the ocean. These membranes are excited by the von Kár- and amplitudes at which free vibrations are known to occur. mán vortex street forming behind a bluff body. Experiments show a number of flow regimes, ranging from poorly coupled, where the The Structure of Round Zero-Net-Mass Flux Jets membrane essentially acts as splitter plate and suppresses vor- J.E. Cater, J. Soria tex shedding, to an optimally coupled state, where the membrane Page: 705-708, Paper no. 27, Paper Code: JW06 oscillates at the natural frequency of the undisturbed wake. The Abstract: This paper presents the results of an experimental inves- details of the interaction between the wake vortices and the mem- tigation of the structure of circular zero-net-mass flux (ZNMF) jets R 4 brane are studied using Particle Image Velocimetry and interpreted at a source Reynolds number of e0 =10 . These jets are generated using topological concepts. by a piston oscillating in a cavity behind a circular orifice. Cross- Large Eddy Simulation of Flow Past a Circular Cylin- correlation digital particle image velocimetry (CCDPIV) was used der to measure instantaneous two-dimensional in-plane velocity fields H.M. Blackburn, S. Schmidt in the far field of the jets. The mean flow quantities of the ZNMF jets are compared with measurements for ‘equivalent’ continuous Page: 689-692, Paper no. 12, Paper Code: JW02 jets in the same apparatus. The results show a larger spreading Abstract: Results are presented of large eddy simulations for smooth rate for the ZNMF jets. The out-of-plane vorticity fields were also subcritical flow past a stationary circular cylinder, at a Reynolds investigated to gain an understanding of the mechanisms respon- number of 3900 where the wake is fully turbulent but the cylinder sible for the difference in spreading rate. A simple model of the boundary layers remain laminar. Results obtained using a spectral velocity profile at the generator is also presented that explains the element discretisation are compared with those obtained with a known behaviour of the velocity field in the developing region of finite volume multiblock method and published experimental re- the flow. sults. Measurements of a Rectangular Confined Jet Flow Interaction Between Two Spheres at Moderate L.P. Chua, A.C. Lua, T.C.W. Loh Reynolds Number Page: 709-712, Paper no. 41, Paper Code: JW07 A.D. Brydon, M.C. Thompson Abstract: The paper presents the measurements of an air jet ex- Page: 693-696, Paper no. 20, Paper Code: JW03 iting from a rectangular nozzle of aspect ratio 6 into a confined Abstract: The flow past two separated spheres placed side-by- chamber using an X-wire probe. Based on the mean velocity re- side is examined using a fully three-dimensional parallel spectral- sults, it was found that self-preservation had been achieved im-
21 mediately after the potential core. Approximate self-preservation Scalar Mixing of Zero-Net-Mass-Flux Jets in Cross- of the confined jet using turbulent intensities was established at flow x/d=14. The centreline velocity decay rate of the confined jet was M. Gordon, J. Soria found to be almost three times less than those of square and circu- Page: 729-732, Paper no. 78, Paper Code: JW12 lar free jets but was about 28% greater than that of plane free jets Abstract: Planar-laser-induced fluorescence (PLIF) is used to inves- with laminar initial conditions and similar Reynolds number. The tigate scalar mixing of circular zero-net-mass flux (ZNMF) jets in spreading rate of the confined jet was found to be quite similar to cross-flow. ZNMF jets are formed using the working fluid of the those of the square and circular free jets but slightly less than the system without net transfer of fluid mass into the system during plane free jets. one period of oscillation. Ensemble-averaged PLIF images of six- Measurements of Turbulent Prandtl Number of a teen different ZNMF jets in cross-flow are studied and compared. Heated Square Jet Two distinct jet structures are seen: single trajectory jets; and mul- L.P. Chua, Y.F. Li, T. Zhou, C.M.S. Yu tiple trajectory jets. Single trajectory jets are characterised by a single maximum concentration across the width of the jet along a Page: 713-716, Paper no. 42, Paper Code: JW08 given trajectory. Multiple trajectory jets are characterised by mul- Abstract: The paper presents the mean and root mean square ve- tiple regions of high concentration issuing from the orifice. Single locity and temperature distributions of a heated square jet flow trajectory jets demonstrate mixing of the bulk of fluid outside the into a stagnant environment. The Reynolds shear stress, heat flux boundary layer, while multiple trajectory jets demonstrate greater and turbulent Prandtl number were also measured by means of penetration. It was observed that there is a critical Strouhal num- a three-wire (i.e. a cold wire in front of an X-wire) probe. It is ber of Stcrit = 0.02 which separates these two regimes. found that the mean velocity and temperature have reached self- preservation nearly immediately after the potential core. The Rey- The Influence of the Nozzle Outlet Shape on Swirl nolds shear stress and heat flux, have however achieved the self- Flow similarity at 30 De and 35 De respectively. The distribution of C. Grubb, S. Rajagopalan Prandtl number here is about constant in the range of 0 < y/Ly < Page: 733-736, Paper no. 81, Paper Code: JW13 0.8, and then increase steeply. The finding has suggested that it Abstract: Flow characteristics of a swirl jet produced by a combina- may have incurred some inaccuracy in the computation fluid me- tion of axial plus tangential injection of air into a nozzle cavity are chanics results by assuming a constant turbulent Prandtl number investigated using hot wire probes and flow visualisation experi- in the jet. ments. Very few measurements seem to have been made on swirl Axis-Switching of a Square Jet jets that are generated using this type of nozzle configuration (Fig- L.P. Chua, Y.F. Li, C.M.S. Yu, T. Zhou ure 1). In this investigation the influence of two different nozzle Page: 717-720, Paper no. 43, Paper Code: JW09 outlet shapes- namely a short constant diameter pipe and a short diffuser, on the jet development is obtained over a range of swirl Abstract: The paper presents the velocity measurements of jet is- numbers from 0.1 to 0.45. Two component velocity measurements suing from a square nozzle into stagnant ambient air. Comparison were made using cross hot wire probes and flow visualisation im- y w of velocity half-width along the - and -axes (parallel to the di- ages were obtained by generating fog by mixing dry ice with hot agonal of the square) showed that there is axis-switching in the water as well as by inserting a cotton thread into the flow. The De/δ present jet. It was found that the large my ratio and low tur- shape of the nozzle outlet geometry seems to have a significant bulent intensity have overcome the adverse effect of the large ratio effect on the swirl jet characteristics. of jet momentum thickness at the diagonal and the flat side re- sulted that the jet has its first axis-switching at 1.75De. Note that On Centerline Distributions of Velocity and Momen- De is jet equivalent diameter and δmy is the momentum thick- tum in Synthetic Jet Actuator Flows ness along the flat side. Further measurements of mean velocity G. Hong, S.G. Mallinson, C. Lee, Q.P. Ha contours at various streamwise locations have indicated that there Page: 737-740, Paper no. 94, Paper Code: JW14 were axis-switching in the present square jet although more mea- Abstract: An experimental investigation of the synthetic jets gen- surement evidence is required. erated by piezoelectrically driven actuators with circular orifice is Velocity Measurements in a Mechanical Precessing reported. The investigation aims to provide information for ac- Jet Flow Using Particle Image Velocimetry tive control of boundary layer flows. Two different configurations K.C. Clayfield, R.M. Kelso, G.M. Schneider, G.J. Nathan of synthetic jet actuator, single- and dual-membrane, were investi- Page: 721-724, Paper no. 48, Paper Code: JW10 gated in conditions without cross flow. The mean and velocity and local momentum along the centerline of the jet are used to charac- Abstract: The present paper describes instantaneous velocity field terize the performance of the actuator. The effect of amplitude and data of the non-reacting flow produced by a mechanical precessing frequency of the driving signals on the actuator’s performance at jet (MPJ) nozzle at a Reynolds number of 20000. Data are obtained Tollmiem-Schlichting frequencies is examined, and the two types using Particle Image Velocimetry (PIV). The data presented show of actuators are compared. the first detailed instantaneous measurements of the flow struc- ture generated by the MPJ nozzle. Velocity and vorticity fields Vorticity Transport Associated with the Dominant show strong consistency with previous point measurements and Vortical Structure of Twin Jets in Crossflow flow visualisation data. The data show the strong entrainment of V. Koláˇr, H. Takao, T. Todoroki, E. Savory, S. Okamoto, the helical MPJ and also suggest that a region of reversed flow ex- N. Toy ists in the near field. Further work should reveal the details of this Page: 741-744, Paper no. 125, Paper Code: JW15 complex flow. Abstract: The present work is concerned with "twin jets in cross- On the Evolution of the Large-Scale Structures in the flow" (TJICF), where the configuration consists of a pair of iden- Far Field of the Plane Jet tical jet nozzles and jet-flow conditions at the nozzle exits. The D. Ewing mean flow velocity vector and associated turbulence statistics of Page: 725-728, Paper no. 71, Paper Code: JW11 the TJICF have been determined using the standard crossed hot- wire anemometry technique. In the present contribution two ge- Abstract: Gordeyev and Thomas[6] recently found that measure- ometrically symmetric TJICF arrangements, namely tandem and ments of the large-scale structures, extracted using Lumley’s POD, side-by-side arrangements (both with a nozzle centre-to-centre sep- were self similar in the intermediate and far field of the plane jet as aration of 5D), are examined, focusing upon the dominant vortical predicted by Ewing[1]. It is demonstrated here that the equations structure rather similar to that of the well-known contrarotating for the two-point velocity correlation tensor have self-similar solu- vortex pair (CVP) of the single JICF. The formation and decay of this tions in the plane jet so that the orthogonal modes extracted using dominant vortical structure is closely associated with the turbulent the POD should be self-similar as Gordeyev and Thomas found. It vorticity transport. The two TJICF arrangements under considera- is also shown that the scaled two-point velocity correlation should tion have their own specific vorticity features which are, firstly, vi- be homogeneous in the mean flow direction if the coordinate is sualized and interpreted in terms of turbulent vorticity fluxes. Sec- rescaled using a logarithmic function. Gordeyev and Thomas did ondly, the vorticity transport analysis shows the vortex-strength not measured the correlation in the mean flow direction so this decay (i.e. circulation decay) as described by the corresponding in- prediction could not be verified. tegral decay-rate formula. The similarities and differences between the vorticity features associated with the two different TJICF (i.e.
22 tandem and side-by-side) arrangements and the single jet case are Bifurcation of Neutrally Buoyant Jets in Stratified examined and discussed. The TJICF flow phenomenon represents Environments an interaction of two single JICFs and the gross qualitative features P.L. Morgan, S.W. Armfield of the vortex formation process of resulting (mean-flow) dominant Page: 761-764, Paper no. 159, Paper Code: JW20 vortical structure are described. Abstract: In homogeneous planar jet’s the existence of any bifur- Effect of a Neighbouring Vibrating Cylinder on a Cir- cation structure depends only on the jet Reynolds number Re. In cular Cylinder Wake the case of a planar jet entering a density stratified medium when W.C. Lai, Yu Zhou, K. Lam, R.M.C. So the jet density is that of the ambient density at the jet entrance, the Page: 745-748, Paper no. 133, Paper Code: JW16 occurrence of a bifurcation will depend on both the jet Reynolds number and the degree of ambient stratification, which is parame- Abstract: This work aims to investigate experimentally the effect of terised by a Richardson number Ri. Direct numerical simulations a neighbouring vibrating cylinder on a circular cylinder near-wake. have been carried out using a non-staggered fractional step scheme In the present investigation, two side-by-side tubes of identical di- to investigate the behaviour of laminar incompressible neutrally d ameter = 10 mm were mounted in a water tunnel; one was sta- buoyant horizontal jets entering a stratified environment. It was tionary and the other forced to vibrate in the lateral direction, up observed that at jet initialisation a jet intrusion front is formed A = . d to a vibration amplitude 0 5 . The dye-marked vortex streets with associated trailing vortex pairs. The intrusion front transits behind the tubes, illuminated by a thin laser sheet, were recorded the domain and for low Reynolds number/low Richardson number T/d using a digital video camera recorder. Two values of , i.e. 2.2 the unsteadiness associated with the initialisation eventually de- T and 3.5 were investigated, where is the cylinder center-to-centre cays and a steady state flow results. At a critical combination of R spacing. The Reynolds number e ranges from 150 to 1000. The Reynolds and Richardson numbers the jet becomes unstable and A/d T/d f /f f effect of , and e s ( s is the vortex shedding frequency bifurcates to an unsteady flow. These results will be presented to- f of an isolated stationary cylinder and e is the structural vibra- gether with critical (Re, Ri) combinations showing the transition tion frequency) is examined on the vortex shedding and the wake behaviour of the flow. structure. Specific attention was given to the occurrence of ’lock- in’, that is, the vortex shedding frequency of the vibrating cylinder Structures in a Round Homogeneous Jet at Low synchronizes with fe. It has been found that the shedding fre- Reynolds Number quency associated with not only the vibrating but also the station- P.L. O’Neill, D. Honnery, J. Soria ary cylinder can be modified as fe/fs approaches unity. Significant Page: 765-768, Paper no. 170, Paper Code: JW21 influence of these parameters has been observed on the flow be- Abstract: The formation of structures in the shear layer of an hind the cylinders in terms of the predominant vortex patterns and unforced, incompressible, free, spatially evolving, round, homo- interactions between vortices. The results are also compared with geneous jet is investigated using flow visualisation and multigrid those of an isolated vibrating cylinder. cross-correlation digital particle image velocimetry (MCCDPIV). It Spreading of Energetic Submerged Fountains Im- has been known for some time that the structures formed in such pinging on a Rigid Surface a jet can either be axisymmetric or helical, however the critical D.M. Holstein , C.J. Lemckert Reynolds number at which these structures occur and at the tran- sition from one form to the other has not been conclusively re- Page: 749-752, Paper no. 137, Paper Code: JW17 solved. Abstract: Laboratory experiments and dimensional considerations were used to investigate the spreading behaviour of negatively Control of an Axisymmetric Jet Using a Passive Ring buoyant axisymmetric vertical fountains after they impinged upon R. Parker, S. Rajagopalan, R.A. Antonia Page: 769-772, Paper no. 176, Paper Code: JW22 a rigid horizontal surface within an initially homogeneous and qui- escent ambient. The distance to which the fountain fluid spread Abstract: This study examines the near field mixing layer develop- radially along the surface before rising back into the ambient (due ment (up to x/D = 5 where x is the longitudinal distance and D to negative buoyancy) was found to be a function of the source is the nozzle exit diameter) of an axisymmetric jet, which is dis- radius, the source Froude number and the depth at which the fluid turbed by placing a thin wire ring axisymmetrically in the mixing was injected. For example, the greater the source Froude number, layer close to the nozzle exit 0.1 ≤ x/D ≤ 0.5. The introduction of and hence initial momentum, the greater the spread of the surface the ring in the mixing layer results in significant changes in the jet flow for the same injection depth and source radius. development, namely a reduction in both the mixing layer growth rate and jet spread rate. The turbulence level in the mixing layer Three Dimensional Transition in a Bickley Jet: Com- is substantially reduced for both longitudinal and transverse fluc- parison of Theory with DNS tuations (approx 20% and 15% respectively). In addition to these R. Mallier, M.C. Haslam reductions the normalised distributions of mean velocity, longitu- Page: 753-756, Paper no. 143, Paper Code: JW18 dinal and transverse velocity fluctuations as well as the skewness Abstract: We consider interactions between varicose and sinuous and flatness factor of these fluctuations, all exhibit improved sim- oblique disturbances in the Bickley jet, using both nonlinear stabil- ilarity. ity theory (in its nonlinear critical layer form) and direct numerical The investigation of the effects of ring position in the axial di- simulation using a spectral method. Nonlinear stability theory in- rection and varying the jet Reynolds number (and thus the wire dicates that a (nonlinear) interaction between the modes should Reynolds number of the ring) indicates that these variations yield occur, and our simulations would seem to support this. nearly identical changes to the characteristics of jet, which sug- Numerical Simulation of Membrane Forcing Effects gests this method of jet control is robust. On Synthetic Jet Actuator Flows Further Evidence for a Transition in Small-Scale Tur- S.G. Mallinson, J.A. Reizes bulence Page: 757-760, Paper no. 144, Paper Code: JW19 B.R. Pearson, P.-Å. Krogstad Abstract: Incompressible laminar Navier-Stokes computations of Page: 773-776, Paper no. 179, Paper Code: JW23 synthetic jet actuator flows have been performed, employing re- Abstract: Measurements of the streamwise component u on the alistic orifice and cavity geometry and membrane forcing charac- center-line of a wake, confirm a transitional behaviour for normal- teristics. The external flow-field exhibits periodic vortex shedding ized high-order moments of ∂u/∂x , within the Taylor micro-scale from the lip of the orifice exit. A vortex is shed into the cavity Reynolds number Rλ range 600 Rλ 900. This Rλ range is from the orifice inlet on the downstroke of the membrane. On 4 equivalent to the large-scale Reynolds number Re range of 1.3x10 the upstroke, this vortex dissipates and there is very little motion 4 Re 2.8x10 . The transition is short lived, with respect to the near the perimeter of the cavity. The results of a series of simula- dissipation length scale η and is not observed for velocity differ- tions suggest a linear relationship between average velocity at the ences ∂u measured over differences greater than 10η. We suggest orifice exit and the product of membrane forcing frequency and that these results are equivalent to previous observations known maximum deflection. as "mixing" transitions - transitions that are associated with the de- velopment of a truly 3-dimensional small-scale turbulent structure - which are most probably a universal feature of turbulent shear flows.
23 Study of Shock Wave Characteristics of Supersonic occur varies in space. This means that the model can predict the Diesel Fuel Jets Using a Shadowgraph Technique wake response (as measured by the oscillation amplitude) almost K. Pianthong, S. Zakrzewski, Masud Behnia, B.E. Milton up to the frequency corresponding to maximum response, but for Page: 777-780, Paper no. 182, Paper Code: JW24 higher forcing frequencies the predictions deviate from the obser- Abstract: In this paper, a technique for the generation of super- vations. sonic liquid (water and diesel fuel) jets is presented. The super- Large Eddy Simulation of a Turbulent Jet sonic liquid jet is generated by the use of a purpose-developed A.T. Webb, N.N. Mansour vertical, single-stage powder gun. With the aid of a shadowgraph Page: 797-800, Paper no. 256, Paper Code: JW29 technique, the characteristics and behaviour of supersonic liquid jets have been visualised. The visual evidence of supersonic diesel Abstract: Here we present the results of a Large Eddy Simulation of fuel jets (velocity around 2000 m/s) generated from a variety of a non-buoyant jet issuing from a circular orifice in a wall, and de- nozzle types is presented. The effects of various nozzle param- veloping in neutral surroundings. The effects of the subgrid scales eters on the jet behaviour are determined. It is found that the on the large eddies have been modeled with the dynamic large characteristics of the leading edge shock wave and jet shape are eddy simulation model applied to the fully 3D domain in spher- significantly related to its nozzle geometry. The jet characteristics ical coordinates. The simulation captures the unsteady motions and its leading edge shock wave are also assessed to determine the of the large-scales within the jet as well as the laminar motions in potential for auto-ignition. the entrainment region surrounding the jet. The computed time- averaged statistics (mean velocity, concentration, and turbulence Metastable Wake States for Flow Past a Cylinder parameters) compare well with laboratory data without invoking Close to a Free Surface an empirical entrainment coefficient as employed by line integral P.J. Reichl, K. Hourigan, M.C. Thompson models. The use of the large eddy simulation technique allows ex- Page: 781-784, Paper no. 194, Paper Code: JW25 amination of unsteady and inhomogeneous features such as the Abstract: For flow at a fixed gap ratio and Froude number, two evolution of eddies and the details of the entrainment process. distinctly different wake states are observed with the flow passing Effect of Initial Conditions on the Turbulence Struc- over the cylinder tending to switch from a state of attachment to tures Various Scales in a Self-Preserving Wake the free surface, to one of separation from it, and then back again Yu Zhou, Hui Li in a pseudo periodic fashion. The two dimensional numerically Page: 801-804, Paper no. 269, Paper Code: JW30 predicted behaviour is found to compare favourably with the ex- Abstract: Initial condition effects in a self-preserving plane wake perimental observations of Sheridan et al. (1995) and Sheridan et have been investigated for two wake generators, i.e. a circular al. (1997), despite the large difference in Reynolds number. cylinder and a screen of 50% solidity. The experimental investi- Stationary and Oscillating Cylinders in the Presence gation uses two orthogonal arrays of sixteen X-wires, eight in the of a Free-Surface (x, y)-plane, i.e. the plane of mean shear, and eight in the (x, z)- J. Carberry, J. Sheridan, D. Rockwell plane, which is parallel to both the cylinder axis and the stream- Page: 785-788, Paper no. 214, Paper Code: JW26 wise direction. The two arrays allow velocity data to be obtained Abstract: The effect of a free-surface, on both stationary and os- simultaneously in the two planes. Measurements were made at cillating cylinders has been studied by simultaneously measuring x/h (x is the streamwise distance downstream of the cylinder and the structure of the near wake and the forces on the cylinder. As h is the height of the wake generator) = 280 for the circular cylin- the stationary cylinder approached the free-surface three different der and 220 for the screen. The wake has been previously veri- wake modes were observed: closer to the surface periodic vortex fied to be approximately self-preserving at these downstream sta- shedding did not occur and the two wake modes differed signifi- tions. The effect of initial conditions on turbulence structures has cantly from the fully submerged Kármán wake, while for the third attracted considerable attention in the literature. Previous stud- mode at deeper submergence depths the response of the wake to ies suggested that the characteristics of the organised motion in a the Kármán instability appeared to be amplified. For both the sta- self-preserving wake could differ as initial conditions vary. Most tionary and oscillating cylinders the presence of the free-surface of these investigations focus on large-scale structures; the role of caused the wake to become non-symmetric and there was a net turbulence structures of other scales has yet to be clarified since negative lift force on the cylinder. it is difficult to extract the structures of these scales using con- ventional vortex-detection techniques. In the present investiga- Velocity-Velocity Difference Correlations and the tion, a two-dimensional orthogonal wavelet transform is used to Sweeping Decorrelation Hypothesis analyse the measured hot-wire data. This technique enables the R.J. Smalley, R.A. Antonia turbulence structures of various scales to be separated and char- Page: 789-792, Paper no. 218, Paper Code: JW27 acterised. Discernible differences are observed between the two ρ Abstract: The correlation, uk,(δu)l between the streamwise ve- wake generators in the turbulence structures of large- down to locity u(x) and the velocity difference δu[≡u(x + r) − u(x)]in intermediate-scales. The differences are quantified in terms of the the streamwise direction, is often used to represent the interac- Reynolds shear stress, kinetic energy and root mean square vortic- tion between the energetic and inertial scales. At infinite Reynolds ity values. number, local isotropy requires the energetic and inertial scales to Quantification of Mixing Characteristics for the Op- ρ be statistically independent. By writing uk,(δu)l in terms of the timisation of Combustion in Rotary Kilns second and fourth-order velocity structure functions, it is shown Jordan J. Parham, G.J. Nathan, Zeyad T. Alwahabi that the correlation can never be zero in the inertial range and is Page: 805-808, Paper no. 279, Paper Code: JW31 therefore an inaccurate representation for the energy-inertial scale Abstract: A planar laser-induced fluorescence technique is used to interaction. The implication of this result on the sweeping decor- study the mixing characteristics from a controllable, fixed geome- relation hypothesis is discussed. try, precessing jet nozzle. Measurements are made to quantify the Application of the Forced Stuart-Landau Model to change in mean and fluctuating centreline conserved scalar con- Cylinder Wake Oscillation centration, probability distribution function and jet spread as a M.C. Thompson, P. Le Gal function of the momentum fraction of an axial shaping jet to pre- Page: 793-796, Paper no. 241, Paper Code: JW28 cessing jet flows. The results are compared with previous small and large-scale combustion measurements and indicate that the Abstract: In this article the application of the forced Stuart-Landau mixing and combustion characteristics are well correlated by the equation to describe the wake flow from a circular cylinder in uni- momentum fraction. Hence the preferred scalar mixing charac- form flow under transverse forcing is investigated. Previous work teristics associated with low NOx emissions and high radiant heat has shown that the forced Stuart-Landau equation predicts multi- transfer for rotary kiln burner designs are identified. valued behaviour can occur over a range of forcing frequencies for a sufficiently large forcing amplitude. In practice, this should mean that the wake is hysteretic as a function of the forcing frequency. Both numerical simulations and experiments have failed to find this predicted hysteresis. The resolution appears to be that forced Landau model predicts that, for a particular forcing amplitude, the range of forcing frequencies over which hysteresis is predicted to
24 Phase Averaged Velocity Field Within a Fluidic Pre- The Role of Unsteadiness within a Central Jet on the cessing Jet Nozzle Structure of a Combined Central and Co-Annular Jet C.Y. Wong, P.V. Lanspeary, G.J. Nathan, R.M. Kelso, T. Flow O’Doherty N.L. Smith, G.J. Nathan Page: 809-812, Paper no. 281, Paper Code: JW32 Page: 825-828, Paper no. 285, Paper Code: JW36 Abstract: A nozzle consisting of a round inlet orifice expanding Abstract: Qualitative and quantitative assessments of the effect of suddenly into a short axisymmetric chamber is the basis of an in- the unsteadiness in a central precessing jet (PJ) on a co-annular jet dustrial burner which produces lower levels of NOx pollution than were made using experimental methods. The central jets were an other, more conventional burners. The jet flow from the inlet ori- unsteady PJ, a simple axial jet, a simple jet directed at 45◦ to the fice reattaches asymmetrically and precesses around the wall of nozzle axis and a conical jet directed at 45◦ to the nozzle axis. The the chamber. Phase-averaged measurements of axial velocity com- central jets were compared on the basis of similar axial momen- ponent in the chamber have shown that the length of the potential tum. The simple directed jet corresponds to case in which the PJ core of the inlet flow is about half that of an unconfined turbulent flow has a precession frequency of zero and the conical jet corre- jet and the velocity decay rate is about twice as large. Entrainment sponds to the case with a precession frequency of infinity. Experi- by the reattaching flow induces a reverse flow in the nozzle. The mental investigations of the near-nozzle region were performed in measurements indicate that this reverse flow has a speed in the or- water using a two-colour planar laser induced fluorescence visual- der of 30% of the forward flow speed. Work by other researchers isation technique. on the effect of counter-flow on jets suggests that interaction be- The visualisations showed that, like the PJ flow, both the directed tween the reverse flow and the reattaching forward flow is largely and the conical jets increased the initial spread of the combined responsible for the high spreading and decay rates of the latter. flow. Nevertheless the PJ flow is fundamentally different from the The Influence of Probe Resolution on Measurements steady analogues. The PJ flow was the only flow to increase the of Fluctuating Scalar and its Dissipation Rate scale of the large-scale, visually coherent, motions in the combined J. Mi, G.J. Nathan flow. This observation was quantified by measurements of jet half- Page: 813-816, Paper no. 282, Paper Code: JW33 width. The central PJ flow increased the annular jet half width by 66%, while the steady jets reduced it by 7% - 32 %. Abstract: This paper investigates the effect of probe resolution on measurements of the scalar fluctuations and the scalar dissipation A Mechanism for Jet Precession in Axisymmetric rate. A simple spectral method is employed to estimate the influ- Sudden Expansions ence of the spatial resolution on both the measured mean squares R.M. Kelso of a fluctuating scalar and its streamwise derivative by filtering the Page: 829-832, Paper no. 287, Paper Code: JW37 signals at different cut-off frequencies. Temperature differential Abstract: A new model describes the flow pattern within a fluidic above ambient acts as a passive scalar for the present investiga- precessing jet chamber. The model offers a simple explanation tion and is measured in the far field of a slightly heated circular of the precessing jet flow and the mechanism which produces the jet. It is found that accurate measurements of the scalar dissipa- precession. The model is used to derive an equation relating the tion rate require the smallest length scale of the scalar fluctuation Strouhal number of precession to the chamber geometry. (defined as the Batchelor scale) to be resolved. However, the res- olution requirement for accurate measurement of the statistics of On the Structural Differences Between Elevated and the scalar fluctuations is much less stringent. Flush Mounted Transverse Jets P.R.E. Cutler, R.M. Kelso Scalar Mixing Characteristics of a Self-Excited Flip- Page: 833-836, Paper no. 288, Paper Code: JW38 Flop Jet Nozzle J. Mi, G.J. Nathan Abstract: Flush mounted and elevated jets in crossflow are stud- Page: 817-820, Paper no. 283, Paper Code: JW34 ied using flow visualisation techniques. Significant differences are demonstrated which suggest that the presence of the flat wall of Abstract: This paper reports an experimental study that investi- the flush mounted jet leads to a significant increase in the mixing gates a self-excited flapping jet nozzle which contains no external rate and a lower jet trajectory compared with the elevated jet. The feedback loop and triggers. We first examine those factors that reasons for these differences are discussed. have significant influence on the Strouhal number, i.e., dimension- less frequency, of the flapping of an initially rectangular jet from Multiphase Flow the nozzle. Then we compare the scalar mixing characteristics of the flapping jet with those of a free (non-flapping) jet. Small tem- Verification of Drag Coefficient Model Through Sim- perature differential above ambient acts as a passive scalar marker ulation of FCI’s Premixing Experiment and is measured with a fine (1.27 µm) cold-wire probe. X. Cao, Y. Tobita Page: 837-840, Paper no. 25, Paper Code: MF01 It is found that the mean scalar decays significantly faster in the Abstract: The QUEOS experiment of the premixing phase of fuel- flapping jet than in the non-flapping jet, indicating enhanced large coolant interactions (FCIs) is simulated to evaluate the drag corre- scale mixing and increased jet spreading due to the flapping mo- lations between the fuel and coolant liquid in the mixing region in tion. Concurrently, however, the flapping motion suppresses fine- FCIs, by the SIMMER-III code. The results of our initial simulation scale scalar mixing. Moreover, the present study suggests that the showed disagreement of the particle cloud advancement in the wa- flapping Strouhal number has a significant impact on the jet mix- ter with the experimental results. Since the FCIs are characterized ing. Higher mixing rates appear to occur at higher Strouhal num- by a configuration where a hot particle/droplet surrounded with bers. vapor film moves in coolant liquid, a new drag correlation is re- Preliminary Study of Oscillating Triangular Jets quired for FCI study. Based on the basic conservative equations, S.K. Lee, P.V. Lanspeary, G.J. Nathan, R.M. Kelso, J. Mi the drag coefficients between a single hot particle/droplet and the Page: 821-824, Paper no. 284, Paper Code: JW35 surrounding coolant liquid under laminar and turbulent flow con- Abstract: A visualisation experiment and measurements with a ditions are developed. The coefficients are expressed as functions Pitot probe show that fluidic instability of a partially confined tri- of Reynolds number, vapor/liquid viscosity and density ratios and angular jet can produce a continuously oscillating flow. The device the other two dimensionless numbers newly introduced in this which produces this flow consists of a triangular inlet orifice ex- study. The proposed correlations are coupled into the SIMMER- panding into a short axisymmetric chamber with an exit lip. These III code and used to simulate the QUEOS experiment. It is shown oscillations occur over a wide range of chamber lengths and ex- that the proposed correlations improve the agreement of the cal- pansion ratios. The amplitude of oscillation and the initial spread- culated results with the experimental data. ing angle of the jet flow are much larger than that of a simple jet Strong Interactions Between Free-Surface Aeration flow. The external oscillating jet has preferred azimuthal direc- and Turbulence Down a Staircase Channel tions which are aligned with the corners of the triangular orifice. Hubert Chanson, Luke Toombes The energy loss coefficient of these jets is significantly lower than Page: 841-844, Paper no. 30, Paper Code: MF02 what can be achieved from a precessing circular jet. Abstract: Interactions between turbulent waters and the atmo- sphere may lead to air-water mixing. This experimental study is focused on the flow down a staircase channel characterised by
25 very-strong interfacial aeration and turbulence. Interfacial aera- known phenomenon is responsible for much of the audible noise tion is characterised by several types of air-water flow structures. generated by liquids in motion. It has applications in bubbly-flow The sizes of bubbles and droplets extend over several orders of analysis software which is useful in food and minerals process- magnitude, and a significant number of bubble clusters was ob- ing, biotechnology, medicine and oceanography. Understanding of served. Velocity and turbulence intensity measurements suggest the detailed processes causing bubble sound emission could yield high levels of turbulence across the entire air-water flow, much more efficient sound-processing algorithms. higher than in classical monophase flow situations. Altogether the Acoustic signals from continuously-sparged laboratory bubbles were study provides a new understanding of the basic interfacial pro- fed through a variable-delay trigger, acquiring high-resolution opti- cesses in aeration cascades. cal images at any desired phase of the bubble information. Numer- Two-Phase Electronic Cooling Using Small Diameter ical simulations were performed by a compressible Navier-Stokes Tubes solver using a level-set interface-tracking method. Thus, each stage F.MD. Chowdhury, F. Kaminaga of the sound-emission process could be compared with data from Page: 845-848, Paper no. 39, Paper Code: MF03 numerical calculations. Abstract: Boiling heat transfer characteristics of Freon R-113 is Experiments revealed that the initial drop in the acoustic signal experimentally investigated in small diameter vertical tubes, D = was co-incident with the contraction of the bubble neck during the 1.45, 2.8 mm and L =100 mm under a wide pressure range of 19 to detachment process. The acoustic signal peak coincided with a jet 269 kPa and a natural circulation condition. Traces of wall temper- of liquid penetrating he bubble after neck breaking. In a first step atures at different elevations indicate that at all heat flux range the towards explaining these observations, the compressible numeri- fluctuation of wall temperature is negligibly small on every system cal model reproduced the theoretical oscillation frequency as well pressure within the present experimental range. Boiling curves in- as the initial drop and subsequent peak on bubble detachment. dicate qualitatively similar to that of normal pool boiling. Except Fluid Flow Through a Channel with Porous Wall Un- the entrance region of the test section the flow is annular in view der a Transverse Magnetic Field of measured vapor flux. Effect of diameter on boiling heat transfer S. Meena is almost consistent with the findings of Klimenko and Ishibashi- Page: 861-864, Paper no. 205, Paper Code: MF07 Nishikawa at system pressures below atmospheric but at pressures above atmospheric, the effect is negligible. Abstract: The problem of steady flow of an electrically conducting incompressible newtonian fluid through a channel with a porous Modelling of Bubble Dynamics in a Venturi Flow wall has been solved by using perturbation method. The behavior with a Potential Flow Method of the velocity profile for different values of Hartmann number and M.J. Gaston, J.A. Reizes, G.M. Evans slip coefficient is shown graphically. Page: 849-852, Paper no. 77, Paper Code: MF04 Numerical Investigation and Measurement of Tran- Abstract: A simple model for cavitation bubble dynamics has been sient Two-Phase Boiling Flow developed using a combination of boundary element methods and G.H. Yeoh, J.Y. Tu, E. Krepper, H.-M. Prasser one-dimensional bubble dynamic equations. Each bubble is as- Page: 865-868, Paper no. 264, Paper Code: MF08 sumed to be spherical and is modelled using a potential source or sink. The strength of the source or sink is governed by one- Abstract: Transient boiling is examined for conditions related to dimensional bubble dynamic equations so that the velocity of the the hypothetical heating of liquids in a storage tank by an ex- growing or decaying bubble at the interface between the vapour ternal fire, with the potential for evaporation of the liquids and and liquid is correctly represented. The model has been imple- the release of toxic gases into the environment. Temperature and mented into computer program to study the growth, collapse, and void fraction distribution data were obtained from an experiment interaction of bubbles as they flow through a venturi. Interactions on water heated in a tank. Numerical simulations were also per- between a bubble starting as a nucleus of gas, the surrounding formed. These generally agreed reasonably well with measure- liquid and the venturi boundaries are described. Although this is ments. a simple model, surprisingly complex interactions can be studied Numerical and Experimental Investigation of High with short computational times and limited computer resources. Speed Two-Phase Condensing Flow of Steam in LP Thus, insights have been gained which otherwise would have been Turbine Cascade extremely difficult to obtain. These are described in terms of the M.Z. Yusoff, Z.A. Mamat, F. Bakhtar, I. Hussein, M.H. bubble history, instantaneous velocity maps and instantaneous Bosrooh, Z. Ahmad stream function contours. Page: 869-872, Paper no. 266, Paper Code: MF09 Viscosity Effects in the Discharge of a Two-Layer Abstract: The present paper describes a work that has been under- Liquid through an Orifice taken to study the effect of wetness in Low Pressure (LP) steam tur- J.L. Liow, M. Juusela, N.B. Gray bines cascade theoretically and experimentally. Theoretical treat- Page: 853-856, Paper no. 140, Paper Code: MF05 ments are done by combining the equations describing the behav- Abstract: The entrainment of either the upper or lower layer of ior of the droplets with the gas dynamic equation. The gas dy- a two fluid system through a tap-hole was investigated experi- namic equation is solved using time marching method applied to mentally. The results showed that for liquids with low viscosities, cell-vertex type finite volume. In order to reproduce realistic high the minimum dimensionless clearance from the taphole before en- speed condensation process as in turbine, test are done in a blow . trainment was related to Fr0 4 in agreement with Craya’s analysis down steam tunnel which is capable of producing supercool steam for Fr > 1. For Fr < 1 surface tension effects resulted in a dimen- without giving kinetic energy. The predicted results are compared sionless clearance smaller than that predicted by Craya’s analy- with the experiments. It is shown that the agreement is very good. sis. For two liquids where the upper liquid was more viscous and . Fr > 1, the results could be fitted to h/d = aFr 0 4, the value of Non-Newtonian Flows a was dependent on the density difference and which liquid layer Parallel Simulation of Viscoelastic Flow Past an Ar- was being withdrawn. When the lower and less viscous liquid was ray of Cylinders by a Unstructured FVM Algorithm withdrawn, a was smaller than Craya’s value of 0.625. When the Hua-Shu Dou, Nhan Phan-Thien upper and more viscous liquid layer was withdrawn, a was gener- Page: 873-876, Paper no. 65 ally larger than Craya’s value. The implications of this study for Abstract: In this paper, the flow of an Oldroyd-B fluid past an ar- the tapping of slag and metal in metallurgical applications are dis- ray of circular cylinders in a channel is simulated by a parallelized cussed. pressure-based Finite Volume Method (FVM) using fine unstruc- Sound Emission Processes on Bubble Detachment tured meshes. The numerical method is using the Discrete Elas- Richard Manasseh, A.V. Bui, J. Sandercock, A. Ooi tic Viscous Split Stress vorticity (DEVSS-omega) formulation and Page: 857-860, Paper no. 145, Paper Code: MF06 the SIMPLER iteration algorithm. The spacing parameter between Abstract: Experimental and numerical studies were conducted on cylinders is selected L=6. The results show that the shear motion the first few milliseconds of a bubble’s sound emission. in the gap between the wall and the cylinder dominates the flow at high Deborah number. Closing of cylinders will alter the behaviour Bubbles can oscillate volumetrically, emitting sound at a frequency of wall shear layers and delay the occurrence of instability. characteristic of their radius and ambient pressure. This well-
26 Visualization of Turbulent Structure in the Drag- instability at the interface dividing the two layers. Regimes char- Reducing Flow of Aqueous Surfactant Solution acterised by either Kelvin-Helmholtz or Holmboe’s instability are Motoyuki Itoh, Y. Kurokawa found to be separated by a well-defined transition. The transi- Page: 877-880, Paper no. 105, Paper Code: NN01 tion from Kelvin-Helmholtz to Holmboe’s instability is compared Abstract: Turbulent structure in the two-dimensional channel flow to scaling arguments that draw on elements of both two-layer hy- of drag-reducing surfactant solution is investigated using hydrogen- draulic theory and linear stability theory. bubble technique. The visual observations are focussed on the Damping of Internal Gravity Waves in Stratified Flu- coherent motions in the near-wall region; i.e., ejections and quasi- ids streamwise vortices. It is revealed that the ejections of near-wall Graham O. Hughes fluid are suppressed in the drag-reducing flows. The ejection could Page: 897-900, Paper no. 98, Paper Code: OG04 not be observed when ’turbulence reduction – drag’ (TRD) is larger than 75%, where TRD is defined using the friction difference be- Abstract: I present a combined experimental and theoretical in- tween laminar and turbulent flows (Gasljevic and Matthys [2]). It is vestigation of damped internal gravity waves in a stratified fluid. found that quasi-streamwise vortices exist even at large TRD above Three parameters determine the flow behaviour - the excitation 80%. The average position of the quasi-streamwise vortex centre frequency of the wavefield, the flow aspect ratio, and a Reynolds becomes more distant from the wall as TRD increases. number based on the strength of the stratification and the flow depth. Damping is found to be very significant for internal grav- Drag Coefficient for Arrays of Cylinders in Flows of ity waves of low frequency (up to at least 0.01N, where N is the Power-Law Fluids buoyancy frequency) over a wide range of flow aspect ratios and P.D.M. Spelt, T. Selerland, C.J. Lawrence, P.D. Lee Reynolds numbers. Page: 881-884, Paper no. 225, Paper Code: NN02 A theory that incorporates spatially uniform damping of internal Abstract: Numerical simulations are presented of flows of power- waves is compared with measurements. This theory provides a sig- law fluids through periodic arrays of aligned cylinders, both creep- nificantly better description of the wavefield than is possible with ing flows and flows with finite inertia. Results are presented for the traditional theory, which neglects damping. drag coefficient of the cylinders and are compared against asymp- totically valid analytical results. Square and hexagonal arrays are Potential Vorticity "Crises" and Western Boundary considered, both for flow in the plane perpendicular to the align- Current Separation ment vector of the cylinders (along the axes of the array as well A.E. Kiss as off-axis flows), and for flow along the cylinders. It is shown Page: 901-904, Paper no. 123, Paper Code: OG05 that the observed strong dependence of the drag coefficient on the Abstract: Process studies have shown that western boundary cur- power-law index (through which the stress tensor is related to the rents of wind-driven midlatitude oceanic gyres can separate from rate-of-strain tensor) for creeping flows can be described at all solid the coast in response to a change in sign of the wind stress curl, area fractions by scaling the drag on a cylinder with appropriate a collision with another western boundary current, outcropping of velocity and length scales. For flows with finite inertia a similar isopycnals or an abrupt change in bottom topography or bound- scaling is found. ary shape. However western boundary current separation is also observed in the "sliced cylinder" model of a wind-driven gyre in Oceanography a circular basin, even though this very simple model lacks all of The Role of Internal Waves in the Layering of Out- these features. flows from Semi-Enclosed Seas We present numerical results which reveal the distribution of po- A.A. Bidokhti, Ross W. Griffiths tential vorticity production and dissipation in this model and shed Page: 885-888, Paper no. 10, Paper Code: OG01 light on the dynamics responsible for the "unprovoked" separation. Abstract: Outflows from semi-enclosed marginal seas typically in- It has been suggested that a "crisis" due to insufficient recovery of volve complex layered structures and inversions in vertical profiles potential vorticity Q in the outer boundary current outflow can of temperature and salinity. We have carried out experiments with result in separation. However our numerical results demonstrate turbulent plumes and their outflows in an enclosed, stratified en- that in fact the "crisis" occurs in the viscous sublayer of the west- vironment. Low frequency internal waves excited by the plume ern boundary current, where fluid columns acquire more Q than outflow itself, as it intrudes into the surrounding stratification at they lost in the interior. The outflow must therefore dissipate this its depth of neutral buoyancy, produce horizontal counter-flowing excess Q before merging with the interior flow. Under strongly shear layers. These ’shearing modes’ lead to branching that breaks nonlinear conditions sufficient viscous dissipation of Q can only up the outflow into a number of layers with a vertical scale deter- be obtained when the outflow separates from the boundary. mined by the structure of the upward propagating wave modes. In Double-Diffusive Plumes in a Homogeneous Envi- the oceans this scale is predicted to be of order 100m. In exper- ronment iments with two diffusing components (T and S) double-diffusive J.S. Turner convection develops thin interfaces and salt fingers between the Page: 905-908, Paper no. 244, Paper Code: OG06 counter-flowing layers. However, the convection is parasitic and Abstract: Laboratory experiments using sources of salt and sugar does not generate the layers or influence their thickness. Oceanic (an analogue system for heat (T) and salt (S)) at opposite ends outflows too are prone to double-diffusive convection but in this of a long tank containing a homogeneous solution of one solute case the convecting layers, 10m to 30m thick, are potentially dis- have been used to investigate the related two-dimensional double- tinguishable from the larger ’shearing mode’ structure. diffusive processes in the ocean. It has been shown that vertical Incipient Motion of Bivalve Shells on Sand Beds un- gradients of T, S and density, and large-scale horizontal interleav- der Currents ing motions, can be generated even when the density of both inputs Subhasish Dey and the initial tank fluid are exactly the same, though the initial Page: 889-892, Paper no. 60, Paper Code: OG02 evolution differs depending on whether the tank contains salt or Abstract: Hydrodynamic forces on a solitary bivalve shell, resting sugar solution. This difference arises because the individual input over a sand bed, are analyzed to determine the critical shear stress plumes are not completely equivalent. Salt diffuses rapidly out of for the condition of incipient motion including the effect of tur- a saline plume in a sugar tank into a surrounding sheath, produc- bulent fluctuations. Three types of shells, namely Coquina Clam, ing stronger convection in the environment than a sugar plume in Cross-barred Chione and Ponderous Ark, were tested experimen- a salt tank. The resulting upward and downward transports of the tally for the condition of incipient motion. The results obtained two properties have been measured in both cases, over a range of using the present model agree satisfactorily with the experimental density differences between source and tank fluid. data. Pipe Flow The Kelvin-Helmholtz to Holmboe Instability Tran- sition in Stratified Exchange Flows Interaction of a Hydraulic Transient with a Leak in A.McC. Hogg, G.N. Ivey a Pipe Flow Page: 893-896, Paper no. 92, Paper Code: OG03 L. Jönsson Page: 909-912, Paper no. 112, Paper Code: PF01 Abstract: A laboratory investigation of exchange flows near the two-layer hydraulic limit is used to examine the generation of shear Abstract: A hydraulic transient due to a rapid flow change in a
27 single, pressurized pipeline will interact with a leak and affect To remedy this shortcoming, an unsteady friction model is often the shape of the transient thus making it potentially possible to employed. Unsteady friction models for laminar flow can be the- identify and locate the leak. This is shown through computations oretically determined and have been successfully used for many and measurements on an experimental 135 m long pipeline set- years. However, the same cannot be said for unsteady friction in up. Moreover, a field test on a 3,500 m long underwater pipeline turbulent flows. A number of empirical unsteady friction models showed promising results for locating an assumed leak. have been formulated, but only perform well for certain unsteady Optimization of Pipelines Containing Fluid Against transient event types. This paper presents a new unsteady friction Divergence model for turbulent flows based on the growth and destruction of K.Y. Maalawi, M.A. Ziada the boundary layer during a transient event. Page: 913-916, Paper no. 142, Paper Code: PF02 Analysis of a Transient in a Pipeline with a Leak Us- Abstract: An exact method is presented for determining the opti- ing Laplace Transforms mal design of fluid-containing pipelines to enhance their resistance X. Wang, M.F. Lambert, A.R. Simpson against divergence instability. The mathematical procedure uses Page: 933-936, Paper no. 262, Paper Code: PF07 the transmission matrix technique along with the method of New- Abstract: A transient or water hammer event is initiated when- ton - Raphson to solve the associated eigenvalue problem. Cal- ever a steady-state condition in a pipeline is disturbed either by a culations are carried out for thin-walled tubes consisting of uni- planned event or accidentally. When the transient reaches a leak, form modules having different length and cross-sectional proper- the transient will be reflected and transmitted, which results in a ties. Design variables include the mean diameter, wall thickness different transient event compared to the transient from the same and length of each module. The model accounts for an elastically pipeline without a leak. In a previous study, an analytical solution supported pipeline in order to cover a wide range of boundary for the variation in hydraulic grade line (HGL) expressed in terms of conditions. Numerical examples demonstrate the efficiency and a Fourier series has been obtained based on a pipeline with known effectiveness of the model in arriving at global optimal solutions. initial conditions and constant boundary conditions. Based on the Spectral Element Based Simulation of Turbulent Pipe analytical solution, a leak detection method was developed previ- Flow ously using leak-induced transient damping. However, The Fourier S. Schmidt, D.M. McIver, H.M. Blackburn, M. Rudman, series approach is not well suited to the case where the boundary G.J. Nathan conditions vary during the transient event. A Laplace transform so- lution approach overcomes this difficulty and is the focus of this Page: 917-920, Paper no. 148, Paper Code: PF03 paper. Normalized hyperbolic governing equations for a pressure Abstract: We present results from direct and large eddy simula- transient in a pipeline with a leak are derived, where the disconti- tions of a turbulent pipe flow where both Cartesian and cylindrical nuity induced by a leak is considered by using a delta function. In formulations of the Navier-Stokes equations have been employed. addition the orifice-leak equation is linearized. The accuracy of the For the large eddy simulations, a conventional eddy viscosity ap- analytical solution has been verified by nonlinear numerical anal- proach has been taken to sub-grid scale stress estimation, in con- yses using the method of characteristics. The effects of a leak on junction with van Driest-type near-wall modification. The results pipeline transients induced by a pulse boundary perturbation and obtained with both DNS and LES are in very good agreement with a continuously changing boundary perturbation are investigated published experimental and numerical data. in detail. Turbulent Pipe Flow: an Analysis of Mean-Flow Wind Engineering Characteristics J.P. Monty, S. Hafez, M.B. Jones, M.S. Chong Surface Roughness and Free Stream Turbulence Ef- Page: 921-924, Paper no. 158, Paper Code: PF04 fects on the Lift Axial Correlation Length of a Circu- lar Cylinder Abstract: An analysis of recent experimental data obtained in a M. Eaddy, W.H. Melbourne, J. Sheridan smooth pipe flow facility at the University of Melbourne is pre- Page: 937-940, Paper no. 66, Paper Code: WE01 sented. In order to ensure a fully developed turbulent flow, mea- surements of mean streamwise velocity profiles were taken almost Abstract: Measurements have been made of the lift axial correla- 400 diameters downstream of the pipe entrance. The resulting tion lengths on aspect 9.1D smooth and rough circular cylinders, at data consists of mean velocity profiles in the Reynolds number Reynolds numbers ranging from 1 ×105 to 3 ×105 in low and high range: 40x103 − 133x103. Two anemometers were used–a Pitot- turbulence flow. Two turbulence integral length scales were used, static tube and a normal hot-wire. Lx = 0.7D and 1.4D. The axial correlation lengths measured on the smooth cylinder in low and high turbulence flow with Lx = 0.7D By comparison with hot-wire data it was possible to determine the agreed with published data. Turbulence with Lx = 1.4D increased accuracy of corrections applied to the Pitot-static tube data. It is the axial correlation length to near 3D. At low roughness levels shown that measured velocity profiles collapse onto the classical the axial correlation length was found to have similar values to logarithmic law when scaled appropriately. Finally, values of the the supercritical regime for a smooth cylinder. At the high surface log law constants are determined. roughness the correlation lengths were found to be approximately Weakly Turbulent Pipe Flow of a Power Law Fluid 3D and dependent only on the level of surface roughness. Tur- M. Rudman, H.M. Blackburn, L.J. Graham, L. Pullum bulence of either scale was found to have little effect on the axial Page: 925-928, Paper no. 202, Paper Code: PF05 correlation length for the high surface roughness. Abstract: Experiment and simulation of the weakly turbulent flow The Effect of Turbulence Intensity on Stall of the of a power law fluid in a pipe are presented. The simulation re- NACA 0021 Aerofoil sults under-predict the superficial flow velocity by approximately K.E. Swalwell, J. Sheridan, W.H. Melbourne 30% and there are qualitative differences in the two sets of veloc- Page: 941-944, Paper no. 235, Paper Code: WE02 ity profiles. Careful examination of experimental and numerical Abstract: This paper presents lift and drag data obtained from methods and results suggests that the cause of the discrepancy is pressure taps on a NACA 0021 aerofoil at Reynolds numbers of a more complex rheology than power law in the experimental fluid. around 3.5 × 105 over a wide range of angles of attack. The air- The numerical results agree well with previously published work foil was subjected to low turbulence flow of turbulence intensity and suggest that the simulation technique is correctly predicting 0.6%, and turbulent flows of length scale 0.56 chords and intensi- turbulence in a power law fluid. ties of 4% and 7%. Turbulence was found to delay stall in a way A Boundary Layer Growth Model for One- that is consistent with the delayed stall seen on Horizontal Axis Dimensional Turbulent Unsteady Pipe Friction Wind Turbines. Increasing the turbulence intensity delayed stall M.F. Lambert, J.P. Vítkovský, A.R. Simpson, A. Bergant until higher angles of attack. Further work is proposed to investi- Page: 929-932, Paper no. 248, Paper Code: PF06 gate the reasons for this delay, to repeat this experiment on a thick Abstract: Unsteady flow in pipe networks is efficiently modeled us- cambered aerofoil and to assess the likely effect on wind turbine ing a one-dimensional flow approximation. It is general practice in performance. engineering to assume a quasi-steady state approximation of the friction for unsteady pipe flows. The result of this approximation is an under-estimation of the damping during fast transient events.
28 Cheung, A.K.W...... 4–AD01 Author Index Chia, P.C...... 11–CF15 Choi, Jung-Il ...... 6–BL04 P–CCCC where P is the page number in this abstract book Chong, M.S...... 6–BL08 7–BL10 7–BL15 and CCCC is the paper code in the timetable. 10–CF10 11–CF21 16–ET07 18–HD04 18–HD08 28–PF04 Chow, M.M...... 18–HD01 A Chow, S...... 13–CF34 Aboutalebi, M.R...... 12–CF26 Chowdhury, F.MD...... 26–MF03 Ahmad, Z...... 26–MF09 Christo, F.C...... 9–CF03 Ahmed, Dewan H...... 20–IF01 Chua, L.P...... 13–OT03 14–OT04 16–ET11 Akroyd, T.J...... 21–IF10 21–JW07 22–JW08 22–JW09 Al-Abdeli, Yasir M...... 9–CO05 Clarke, S.R...... 17–HL01 Alam, F...... 3–AA01 4–AA05 Clayfield, K.C...... 22–JW10 Allen, J.J...... 21–JW01 Cleary, Paul ...... 10–CF04 12–CF22 Alwahabi, Zeyad T...... 24–JW31 Coantic, M...... 16–ET10 Anderson, C.S...... 16–ET08 Cole, T.R...... 5–AD06 Anderson, J.G...... 14–OT11 Cooper, Paul ...... 14–OT05 14–OT06 20–IF02 Anselmet, F...... 13–OT01 16–ET10 Cummins, S.J...... 14–OT07 Antonia, R.A...... 6–BL06 7–BL17 10–CF05 Cutler, P.R.E...... 25–JW38 13–OT01 16–ET10 16–ET11 23–JW22 24–JW27 Arifin, N.M...... 18–HD05 D Armfield, S.W...... 13–OT02 23–JW20 Dabrowski, P.P...... 6–BL05 Arshadi, Kh...... 19–HD16 Dally, B.B...... 9–CO09 Danaila, L...... 13–OT01 Debroux, François ...... 10–CF04 12–CF22 B Denier, J.P...... 6–BL05 6–BL07 Babanin, A.V...... 3 Derzho, O.G...... 18–HD02 Bakhtar, F...... 26–MF09 Dey, Subhasish ...... 27–OG02 Barlow, R.S...... 9–CO09 Dimotakis, Paul E...... 2 Barth, W...... 13–CF34 Ding, Daoyang ...... 12–CF28 Beaubert, François ...... 13–CF33 Djavareshkian, M.H ...... 11–CF11 Behnia, Masud ...... 12–CF29 24–JW24 Djenidi, L...... 6–BL06 7–BL17 10–CF05 Berera, F.L...... 8–BL23 Donohoo, S.M...... 17–HL02 Bergant, A...... 28–PF06 Doolan, Con ...... 8–CO02 Bertoglio, J.P...... 9–CF01 Dou, Hua-Shu ...... 426 Bidokhti, A.A...... 27–OG01 Bilger, Robert W...... 9–CO08 Bisceglia, S...... 6–BL06 E Blackburn, H.M...... 6–BL01 10–CF06 Eaddy, M...... 28–WE01 12–CF25 21–JW02 28–PF03 28–PF05 Elston, J.R...... 10–CF06 Boger, D.V...... 3 Erm, Lincoln P...... 15–ET02 Borgas, M.S...... 5–AR01 Evans, G.M...... 26–MF04 Bosrooh, M.H...... 26–MF09 Ewing, D...... 22–JW11 Boyes , K.M...... 17–HL02 Brackbill, J.U...... 14–OT07 Brandner, P.A...... 19–HD15 F Broutman, Dave ...... 19–HD11 Farrow, D.E...... 18–HD03 Brown, R...... 10–CF09 Flay, Richard G. J...... 4–AD04 Brydon, A.D...... 21–JW03 Fletcher, D.F...... 10–CF08 Bui, A.V...... 9–CF02 26–MF06 Fonarev, A.S...... 10–CF07 Bull, M.K...... 6–BL03 8–BL23 21–JW04 Forsyth, C...... 19–HD09 Buttsworth, D.R...... 17–GD04 G C Gaston, M.J...... 26–MF04 Cao, X...... 25–MF01 George, W.K...... 2 Carberry, J...... 21–JW05 24–JW26 Gordon, M...... 22–JW12 Cardoso, S.S.S...... 18–HD01 Govindarajan, Rama ...... 2 Carey, G...... 13–CF34 Gradinscak, M...... 20–IF07 Carper, M.A...... 5–AD13 Graham, L.J...... 28–PF05 Cashman, K.V...... 14–OT08 Gray, N.B...... 26–MF05 Cater, J.E...... 21–JW06 Gregory, P.A...... 18–HD04 Chan , W.K...... 14–OT04 Griffiths, Ross W...... 14–OT08 15–OT14 Chanson, Hubert ...... 25–MF02 27–OG01 Chen, Frank L...... 20–IF01 Grimshaw, R...... 18–HD02 Chen, Yung-Cheng ...... 8–CO01 9–CO08 Grubb, C...... 22–JW13
29 Gualtieri, Paola ...... 8–BL22 Kerr, R.C...... 14–OT08 14–OT12 Guo, B...... 10–CF08 Kim, Kyoungyoun ...... 7–BL11 Kirk, B...... 13–CF34 Kiss, A.E...... 27–OG05 H Klaka, K...... 18–HD07 Ha, Q.P...... 22–JW14 Kobayashi, T...... 15–OT16 Hafez, S...... 7–BL15 28–PF04 Koláˇr, V...... 22–JW15 Halatchev, I.A...... 6–BL07 Kollmann, W...... 8–CO04 11–CF21 Hargreaves , D.J...... 10–CF09 Kosasih, P.B...... 7–BL12 15–OT13 Hashim, I...... 18–HD05 Kostas, J...... 18–HD08 Haslam, M.C...... 23–JW18 Krepper, E...... 26–MF08 Hellstedt, A.K...... 6–BL08 Krogstad, P.-Å...... 5–AD13 7–BL13 23–JW23 Higgins, K...... 10–CF10 Krokstad, J.R...... 18–HD07 19–HD13 Ho, D.K.H...... 17–HL02 Kunkel, G.J...... 7–BL14 Hogg, A.McC...... 27–OG03 Kurokawa, Y...... 27–NN01 Holford, Joanne M...... 4–AD02 17–GD01 18–HD01 Holstein , D.M...... 23–JW17 L Hong, G...... 22–JW14 Lai, J.C.S...... 5–AD12 Honnery, D...... 23–JW21 Lai, K.L...... 6–BL03 21–JW04 Hooper, J.D...... 4–AD03 Lai, W.C...... 23–JW16 Hossain, Monir ...... 8–CO03 Lam, K...... 23–JW16 Hothersall, R...... 20–IF03 Lam, S.S...... 4–AD05 Hourigan, K...... 3–AA02 4–AA04 4–AD01 Lamaison, G...... 9–CF01 11–CF12 11–CF13 11–CF14 11–CF17 Lambert, M.F...... 28–PF06 28–PF07 12–CF23 12–CF24 12–CF27 15–OT15 Langrish, T.A.G...... 10–CF08 18–HD06 20–IF05 24–JW25 Lanspeary, P.V...... 25–JW32 25–JW35 Hughes, Graham O...... 15–OT14 27–OG04 Lasserre, J-J...... 16–ET10 Hunt, Gary R...... 4–AD02 14–OT05 17–GD01 Lavoie, P...... 15–ET04 Huntsman, I...... 14–OT09 20–IF03 Lawrence, C.J...... 27–NN02 Hussain, Fazle ...... 2 Lee, C...... 22–JW14 Hussein, I...... 26–MF09 Lee, P.D...... 27–NN02 Huynh, B.P...... 15–ET03 20–IF04 Lee, S.K...... 25–JW35 Le Gal, P...... 24–JW28 Lei, Chengwang ...... 11–CF16 I Lemckert, C.J...... 19–HD09 23–JW17 Ichimiya, M...... 6–BL09 Leonardi, E...... 13–CF30 Ichimiya, T...... 15–OT16 Li, D...... 5–AD11 Iguchi, Tadashi ...... 13–CF32 Li, E.B...... 15–OT13 Itoh, Motoyuki ...... 19–HD14 27–NN01 Li, Hui ...... 24–JW30 Ivey, G.N...... 327–OG03 Li, J.D...... 16–ET05 Li, Y.F...... 22–JW08 22–JW09 Liddell, B...... 14–OT09 J Lim, T.T...... 5–AD08 11–CF21 15–OT18 Jackson, Peter S...... 4–AD04 Linden, Paul F...... 214–OT05 17–GD01 Javam, A...... 13–OT02 Liow, J.L...... 26–MF05 Johansson, T.G...... 2 Liow, K...... 3–AA02 Johnson, E.R...... 17–HL01 Liu, F...... 11–CF17 Johnson, Peter W...... 16–ET06 Liu, Jinpei ...... 12–CF28 Johnson, S.A...... 11–CF12 Liu, Zeqin ...... 20–IF02 Johnston, Michael S...... 4–AD04 Loh, T.C.W...... 21–JW07 Jones, M.B...... 6–BL08 7–BL10 16–ET07 Lopez, J.M...... 6–BL01 28–PF04 Lua, A.C...... 21–JW07 Jones, M.C...... 11–CF13 11–CF14 Jönsson, L...... 27–PF01 Joubert, P.N...... 7–BL15 18–HD04 M Juusela, M...... 26–MF05 Maalawi, K.Y...... 28–PF02 Madhani, Jehangir T...... 10–CF07 17–GD05 Mallier, R...... 23–JW18 K Mallinson, S.G...... 22–JW14 23–JW19 Kaminaga, F...... 26–MF03 Mamat, Z.A...... 26–MF09 Karpetis, A.N...... 9–CO09 Manasseh, Richard ...... 16–ET12 26–MF06 Kaspersen, J.H...... 7–BL13 Manders, M...... 14–OT09 Kataoka, K...... 19–HD10 Mansour, N.N...... 24–JW29 Katselis, G...... 14–OT11 Marusic, I...... 7–BL14 8–BL20 Kelso, R.M...... 3–AA03 21–JW01 22–JW10 Masri, Assaad R...... 8–CO01 9–CO05 25–JW32 25–JW35 25–JW37 25–JW38 Matheson, N...... 4–AD05 Kennedy, I.M...... 8–CO04 McBean, I.W...... 11–CF17
30 McDonald, C...... 14–OT09 McIver, D.M...... 28–PF03 Q Meena, S...... 26–MF07 Quadros, C.E...... 17–GD02 Melbourne, W.H...... 28–WE01 28–WE02 Mi, J...... 25–JW33 25–JW34 25–JW35 Milbank, J...... 3–AA03 R Milton, B.E...... 24–JW24 Rahaman, M.F...... 17–GD03 Miyanaga, K...... 15–OT16 Rajagopalan, S...... 22–JW13 23–JW22 Moin, P...... 2 Reichl, P.J...... 15–OT15 24–JW25 Moinuddin, K.A.M...... 7–BL15 Reizes, J.A...... 13–CF30 23–JW19 26–MF04 Mole, Lindsay ...... 16–ET06 Renilson, M.R...... 18–HD07 Monty, J.P...... 28–PF04 Revel, A...... 15–ET03 Morgan, P.L...... 23–JW20 Rhodes, N...... 16–ET09 Mullarney, Julia C...... 15–OT14 Roberts, J.L...... 7–BL18 Mullinger, Peter ...... 3 Rockwell, D...... 21–JW05 24–JW26 Mununga, L...... 20–IF05 Rottman, James W...... 19–HD11 Rottman, J.W...... 19–HD12 Rudman, M...... 9–CF02 28–PF03 28–PF05 N Ryan, Kris ...... 12–CF24 Naida, M.A...... 10–CF07 Narasimha, Roddam ...... 2 Naser, Jamal ...... 8–CO03 17–GD03 20–IF01 S Nathan, G.J...... 22–JW10 24–JW31 25–JW32 Sakai, T...... 15–OT16 25–JW33 25–JW34 25–JW35 Sandercock, J...... 26–MF06 25–JW36 28–PF03 Savory, E...... 22–JW15 New, T.H...... 5–AD08 Sawford, B.L...... 6–AR02 Ng, Eton Y...... 16–ET06 Schmidt, S...... 12–CF25 21–JW02 28–PF03 Nguyen, Q.D...... 21–IF10 Schneider, G.M...... 22–JW10 Nickels, T.B...... 7–BL16 Schoppa, Wade ...... 2 Nishizawa, N...... 7–BL10 16–ET07 Selerland, T...... 27–NN02 Nomura, K.K...... 19–HD12 Semercigil, S. Eren ...... 16–ET08 20–IF06 Norrish, J...... 14–OT06 20–IF07 Noui-Mehidi, M.N...... 19–HD10 Serizawa, Akimi ...... 13–CF31 Novozhilov, V...... 11–CF19 Seyedein, S.H...... 12–CF26 Shao, L...... 9–CF01 Sharifian, S.A...... 17–GD04 O Sheard, G.J...... 12–CF27 O’Doherty, T...... 9–CO07 25–JW32 Sheridan, J...... 10–CF06 21–JW05 24–JW26 Ohmura, N...... 19–HD10 28–WE01 28–WE02 Shervani-Tabar, M.T...... 19–HD16 Okamoto, S...... 22–JW15 Siegenthaler, Alfred ...... 17–GD05 O’Neill, P.L...... 11–CF20 23–JW21 Simpson, A.R...... 28–PF06 28–PF07 Ong, K.S...... 13–OT03 14–OT04 Siores, Elias ...... 20–IF01 Ooi, A...... 10–CF10 11–CF21 26–MF06 Slater, G...... 14–OT06 Otto, S.R...... 5–AD06 8–BL21 Smalley, R.J...... 6–BL06 24–JW27 Oyewola, O...... 7–BL17 Smith, A.G...... 17–GW01 Smith, D.H...... 17–GD06 P Smith, N.L...... 25–JW36 Pai, R...... 10–CF09 Smits, A.J...... 221–JW01 Panchapakesan, N.R...... 5–AD07 So, R.M.C...... 23–JW16 Parham, Jordan J...... 24–JW31 Soh, W.K...... 20–IF08 Parker, K...... 5–AD08 5–AD09 Soodphakdee, Denpong ...... 12–CF29 Parker, R...... 23–JW22 Soria, J...... 5–AD07 5–AD08 5–AD09 11–CF20 Parmigiani, H.S...... 15–ET03 11–CF21 15–OT18 18–HD08 Patterson, John C...... 311–CF16 21–JW06 22–JW12 23–JW21 ...... 27–NN02 Pearson, B.R...... 5–AD13 23–JW23 Spelt, P.D.M...... 13–CF30 Phan-Thien, Nhan ...... 426 Spong, E.C...... 8–CO01 Pianthong, K...... 24–JW24 Starner, Sten H...... 13–CF31 Pollard, A...... 15–ET04 Stevanovic, Vladimir D. 13–CF32 Porté-Agel, F...... 7–BL14 Stokes, Y.M...... 21–IF09 Prakash, Mahesh ...... 10–CF04 12–CF22 Stosic, Zoran V...... 13–CF31 13–CF32 Prasser, H.-M...... 26–MF08 Stretch, D.D...... 19–HD12 Pregnalato, C.J...... 12–CF23 Subbareddy, P.K...... 8–BL20 ...... 8–BL22 Pulci Doria, Guelfo Sudo, C...... 6–BL09 ...... 28–PF05 Pullum, L. Sundaravadivelu, K...... 11–CF15 14–OT10 Sung, Hyung Jin ...... 6–BL04 7–BL11 Swalwell, K.E...... 28–WE02 Syred, C.P...... 9–CO07
31 Y Yeoh, G.H...... 26–MF08 T Yeung, P.K...... 5–AR01 Tabeling, P...... 2 Young, I.R...... 3 Takao, H...... 22–JW15 Young, J...... 5–AD12 Tan, B.T...... 4–AA04 4–AD01 Yu, C.M.S...... 22–JW08 22–JW09 Tan, W.H...... 15–OT18 Yu, S.C.M...... 11–CF15 13–OT03 14–OT04 Techet, A.H...... 21–JW01 Yusoff, M.Z...... 26–MF09 Teubner, M.D...... 17–GW01 Thompson, M.C...... 3–AA02 4–AA04 4–AD01 11–CF12 11–CF13 11–CF14 11–CF17 12–CF23 12–CF24 12–CF27 15–OT15 Z Zakrzewski, S...... 24–JW24 18–HD06 20–IF05 21–JW03 24–JW25 Zhou, T...... 13–OT01 13–OT03 16–ET10 24–JW28 16–ET11 22–JW08 22–JW09 Tieu, A.K...... 7–BL12 15–OT13 Zhou, Yu ...... 23–JW16 24–JW30 Tobita, Y...... 25–MF01 Zhu, Yonggang ...... 16–ET12 Todoroki, T...... 22–JW15 Ziada, M.A...... 28–PF02 Toombes, Luke ...... 25–MF02 Zimmer, G...... 3–AA01 4–AA05 Touil, H...... 9–CF01 Toy, N...... 22–JW15 Truong, Tam D...... 20–IF06 Tso, C.P...... 11–CF15 14–OT10 Tu, J.Y...... 12–CF29 26–MF08 Tuck, E.O...... 8–BL19 Tucker, A...... 14–OT09 Turan, Özden F...... 16–ET08 20–IF06 20–IF07 Turner, J.S...... 27–OG06 U Uddin, A. K. Mesbah ...... 8–BL20 V Vauquelin, O...... 16–ET09 Venayagamoorthy, S.K...... 19–HD12 Viazzo, Stéphane ...... 13–CF33 Viot, J...... 16–ET09 Vítkovský, J.P...... 28–PF06 von Ellenrieder, K.D...... 5–AD09 15–OT18 W Walker, G.J...... 7–BL18 19–HD15 Wang, H...... 2 Wang, X...... 28–PF07 Wang, Xiao-Liang ...... 19–HD14 Watkins, Simon ...... 3–AA01 3–AA03 4–AA05 4–AD03 5–AD10 16–ET06 Watmuff, J.H...... 2 Watson, C.E...... 8–BL21 Webb, A.T...... 24–JW29 Whitfield, A...... 15–OT16 Willis, B...... 20–IF08 Wollblad, C...... 2 Wong, C.Y...... 25–JW32 Wong, Y.W...... 14–OT04 Wood, D.H...... 5–AD11 Wu, Jie ...... 16–ET12 Wu, Shiqiang ...... 12–CF28 Wypych, Peter W...... 20–IF02 X Xia, J...... 19–HD13 Xu, Chun-Xiao ...... 6–BL04
32 Paper Code Index
Plenary Lectures ...... 2 CF10 ...... 10 HD05 ...... 18 JW31 ...... 24 Review Topics ...... 2 CF11 ...... 11 HD06 ...... 18 JW32 ...... 25 CF12 ...... 11 HD07 ...... 18 JW33 ...... 25 AA01 ...... 3 CF13 ...... 11 HD08 ...... 18 JW34 ...... 25 AA02 ...... 3 CF14 ...... 11 HD09 ...... 19 JW35 ...... 25 AA03 ...... 3 CF15 ...... 11 HD10 ...... 19 JW36 ...... 25 AA04 ...... 4 CF16 ...... 11 HD11 ...... 19 JW37 ...... 25 AA05 ...... 4 CF17 ...... 11 HD12 ...... 19 JW38 ...... 25 AD01 ...... 4 CF19 ...... 11 HD13 ...... 19 MF01 ...... 25 AD02 ...... 4 CF20 ...... 11 HD14 ...... 19 MF02 ...... 25 AD03 ...... 4 CF21 ...... 11 HD15 ...... 19 MF03 ...... 26 AD04 ...... 4 CF22 ...... 12 HD16 ...... 19 MF04 ...... 26 AD05 ...... 4 CF23 ...... 12 HL01 ...... 17 MF05 ...... 26 AD06 ...... 5 CF24 ...... 12 HL02 ...... 17 MF06 ...... 26 AD07 ...... 5 CF25 ...... 12 IF01 ...... 20 MF07 ...... 26 AD08 ...... 5 CF26 ...... 12 IF02 ...... 20 MF08 ...... 26 AD09 ...... 5 CF27 ...... 12 IF03 ...... 20 MF09 ...... 26 AD10 ...... 5 CF28 ...... 12 IF04 ...... 20 NN01 ...... 27 AD11 ...... 5 CF29 ...... 12 IF05 ...... 20 NN02 ...... 27 AD12 ...... 5 CF30 ...... 13 IF06 ...... 20 OG01 ...... 27 AD13 ...... 5 CF31 ...... 13 IF07 ...... 20 OG02 ...... 27 AR01 ...... 5 CF32 ...... 13 IF08 ...... 20 OG03 ...... 27 AR02 ...... 6 CF33 ...... 13 IF09 ...... 21 OG04 ...... 27 BL01 ...... 6 CF34 ...... 13 IF10 ...... 21 OG05 ...... 27 BL03 ...... 6 CO01 ...... 8 JW01 ...... 21 OG06 ...... 27 BL04 ...... 6 CO02 ...... 8 JW02 ...... 21 OT01 ...... 13 BL05 ...... 6 CO03 ...... 8 JW03 ...... 21 OT02 ...... 13 BL06 ...... 6 CO04 ...... 8 JW04 ...... 21 OT03 ...... 13 BL07 ...... 6 CO05 ...... 9 JW05 ...... 21 OT04 ...... 14 BL08 ...... 6 CO07 ...... 9 JW06 ...... 21 OT05 ...... 14 BL09 ...... 6 CO08 ...... 9 JW07 ...... 21 OT06 ...... 14 BL10 ...... 7 CO09 ...... 9 JW08 ...... 22 OT07 ...... 14 BL11 ...... 7 ET02 ...... 15 JW09 ...... 22 OT08 ...... 14 BL12 ...... 7 ET03 ...... 15 JW10 ...... 22 OT09 ...... 14 BL13 ...... 7 ET04 ...... 15 JW11 ...... 22 OT10 ...... 14 BL14 ...... 7 ET05 ...... 16 JW12 ...... 22 OT11 ...... 14 BL15 ...... 7 ET06 ...... 16 JW13 ...... 22 OT12 ...... 14 BL16 ...... 7 ET07 ...... 16 JW14 ...... 22 OT13 ...... 15 BL17 ...... 7 ET08 ...... 16 JW15 ...... 22 OT14 ...... 15 BL18 ...... 7 ET09 ...... 16 JW16 ...... 23 OT15 ...... 15 BL19 ...... 8 ET10 ...... 16 JW17 ...... 23 OT16 ...... 15 BL20 ...... 8 ET11 ...... 16 JW18 ...... 23 OT18 ...... 15 BL21 ...... 8 ET12 ...... 16 JW19 ...... 23 PF01 ...... 27 BL22 ...... 8 GD01 ...... 17 JW20 ...... 23 PF02 ...... 28 BL23 ...... 8 GD02 ...... 17 JW21 ...... 23 PF03 ...... 28 CF01 ...... 9 GD03 ...... 17 JW22 ...... 23 PF04 ...... 28 CF02 ...... 9 GD04 ...... 17 JW23 ...... 23 PF05 ...... 28 CF03 ...... 9 GD05 ...... 17 JW24 ...... 24 PF06 ...... 28 CF04 ...... 10 GD06 ...... 17 JW25 ...... 24 PF07 ...... 28 CF05 ...... 10 GW01 ...... 17 JW26 ...... 24 WE01 ...... 28 CF06 ...... 10 HD01 ...... 18 JW27 ...... 24 WE02 ...... 28 CF07 ...... 10 HD02 ...... 18 JW28 ...... 24 CF08 ...... 10 HD03 ...... 18 JW29 ...... 24 CF09 ...... 10 HD04 ...... 18 JW30 ...... 24
33