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Welcome to the latest wind engineering in the in what I hope will UK and act as a catalyst become a regular series for increased industry and of newsletters. Those of academic collaboration. you who attended the AGM will have heard that In keeping with tradition, we have a dynamic young this year we will hold the members group who are society’s most prestigious the driving force behind Scruton Lecture on the this newsletter (hence, 23rd November. Prof my optimism that such Chris Letchford from communications will be Rensselaer Polytechnic more frequent). They Institute, will deliver what have done a tremendous I am sure will be a thought In this issue Library Central NOAA ©NOAA Photo Library, job in revamping the provoking (and knowing SPECIAL newsletter and producing Chris, possibly an amusing INTERVIEW CODES & WIND UK Wind FEATURE STANDARDS ISSUES copy. Having produced lecture) on The Evolution the newsletter many of Wind Engineering: From Simulating a Paul Freathy: Wind Speed Galloping of years ago, I know from Storms to Thunderstorms. Engineering tornado A personal Probabilities and lampposts first hand experience how I look forward to seeing viewpoint Return Periods during a difficult it can be ensuring you there. Also taking Society on Wind snowstorm that appropriate copy place this year will be the Engineering is available on time so WES Research Day on 14th I would like to take this October at the University opportunity to strongly of Reading. This event will encourage you all to send showcase the best of our Newsletter any relevant news (no up and coming researchers matter how small) to and appropriately is being [email protected]. arranged by our young Issue I - 2015 2 5 6 7 members group. I am pleased to note that WES EVENING INTERNATIONAL ANNOUNCEMENTS as part of the groundwork The young members group NEWS LECTURES COMMUNITY laid by John Kilpatrick have already had a positive WES Research we have been involved in impact, if you would like to Job Posting Bridge 14th International Day 2015 shaping the Engineering contribute to the society Aerodynamics – Conference on 14 October 2015 and Physical Sciences (irrespective of age) then WES Young Past Present and Wind Engineering Research Council (EPSRC) please feel free to contact Members’ Future (ICWE), 2015 Scruton Lecture thoughts on wind tunnel us with your ideas. Group 23 November infrastructure. The EPSRC Submit your Symposium on 2015 roadmap is available to Prof. Mark Sterling contribution at: the Dynamics and read at http://www.nwtf. University of Birmingham [email protected] Aerodynamics of International ac.uk/ and your comments Cables (SDAC) Wind Engineering are strongly encouraged. 2014 Events and Call The roadmap will for Papers hopefully strengthen the 8 9 10 12 column Chairman’s Simulating a tornado by Stefanie Gillmeier and Chris Smith, School of Civil Engineering, University of Birmingham, UK Tornadoes been constructed at the University of Birmingham following the design A Tornado is a violent rotating column of employed by Matsui and Tamura (2009). air attached to a thunderstorm base and in contact with the ground. Tornadoes On the simulator floor a 64 channel cause large pressure gradients and high surface pressure system has been wind velocities on a relatively small installed which enables an instantaneous spatial and temporal scale compared map of the surface pressure to be to other meteorological events in the obtained. Velocity measurements atmosphere. For that reason tornadoes Figure 2. Birmingham tornado on the 28 July 2005 (a) and illustration of damage caused by have been recorded using a high- are known as the world’s most powerful the Birmingham tornado (b) (BBC, 2005). resolution TFI Cobra probe mounted on and destructive wind events. (Mishra, a manually movable traverse system. et al., 2008) occur (Provic, 2013). Nevertheless it is (1983) and Bienkiewicz and Dudhia Experimental results have been carried important to recognize that tornadoes (1993) demonstrated that swirling out for four different swirl ratios (S) In Europe, tornadoes are not as strong also occur in other countries of the world. wind loads can induce a pressure force (S = 0.12, S = 0.23, S = 0.40, S = 0.92) and common as in parts of the US where Dr Pieter Groenemeijer, director of the some 3-5 times greater than the effects at two different heights above the 75% of the world’s known tornadoes European Severe Storms Laboratory, produced by a straight line wind of simulator surface (h = 0.05m, h = 0.18m) estimates that about 300 tornadoes per similar wind velocity. (Figure 4). The swirl ratio is a measure of year are spotted in Europe (Du Brulle, the amount of rotational energy in the 2013) (Figure 1). The field of tornado research is relatively vortex relative to the convective energy young and for that reason little is known and correlates well with the vortex A well-known example in the UK is the about the physical interaction process structure (Wan and Chang, 1971). For Birmingham tornado which occurred between the flow and pressure field of the purposes of this work the swirl ratio on the 28 July 2005 (Figure 2a), when tornadoes and structures. Furthermore, is defined by S = (tan(α)) / 2a (although a tornado rated as an F2 on the Fujita datasets of full-scale tornadic events it is acknowledged that other definitions scale touched down in the southwest of are limited and as such recourse is often exist). Birmingham, rendering 200 properties made to physical simulations. See for structurally unstable (Figure 2b) and example Church et al., (1979) at Purdue It was observed that as the swirl ratio causing an estimated £40m damage University, Haan et al., (2008 ) at Iowa increases, the vortex core also increases to properties in that areas (BBC news, State University, Mishra et al., (2008) (when S = 0.12, R ~ 0.06m (Figure 4a); 2005). at Texas Tech University, Hashemi et when S = 0.92; R ~ 0.14m (Figure 4d)). al., (2010) and Refan et al., (2014) at This supports the findings of previous Figure 1. Tornado events in Europe between Simulating a Tornado the University of Western Ontario and work (Ward, 1972; Davies-Jones, 1973). 2000-2012 as recorded in the European Severe Sabareesh et al., (2012) at the Tokyo Furthermore, for S = 0.12, S = 0.23 and Weather Database. The colours and sizes of Former engineering practise was to treat Polytechnic. S = 0.40 (Figure 4a-c) the core radius R the symbols refer to the classification of the the pressure effects of tornadic events appears to be a function of height. tornado on the Fujita scale. © ESSL (taken similar to that one induced by straight Recently, a small scale tornado- from Du Brulle, 2013) line winds. However, Jischke and Light like vortex generator (Figure 3) has The flow characteristics of the simulated 2 UK WIND ENGINEERING SOCIETY [ Issue I - 2015 ] Radius on Swirl Ratio in a Tornado Simulator. J. Atmos. Sci. 30, pp1427-1429. Du Brulle, 2013. European Commission, Research & Innovation. Horizon, The EU Research & Innovation Magazine. 300 tornadoes hit Europe every year. http://horizon-magazine.eu/ article/300-tornadoes-hit- europe-every-year_en.html (accessed on 03/09/2015) Figure 3: University of Birmingham TVS - Schematic Diagram (top) and 3D visualisation (bottom) Haan, Sarkar, Gallus, 2008. Design, construction and tornado-like vortices have been Future work performance of a large compared to three analytical models, tornado simulator for wind viz., the Rankine model, the Burgers- Plans are underway to construct a engineering applications. Rott model and the Sullivan model larger tornado-vortex generator at the Engineering Structures 30, pp 1146-1159. (Figure 5). All of the analytical models University of Birmingham and this work assume a flow filed with a tangential be extended in the newly built simulator. Hashemi, Gurka, Hangan, velocity component that is independent The larger generator will enable a more 2010. Experimental of height. However, the experimental in depth study of the flow field to be investigation of tornado- results show a change in the vortex core undertaken and the issue of scale to be like vortex dynamics with radius with height (Figure 2 a-c). investigated. swirl ratio: The mean and turbulent flow fields. J. Wind Eng. Ind. Aerodyn. 98, pp In conclusion, this analysis shows that References 936–944. none of the analytical models appear to accurately predict the tangential Bienkiewicz, Dudhia, 1993. Physical modeling Jischke, Parang, 1974. velocity across the range of swirl rations of tornado-like flow and tornado effects Properties of Simulated and heights investigated (Figure 5). on building loading. Proceeding of 7th US Tornado-Like Vortices. J. However, the Sullivan and Burgers National Conference on Wind Engineering, Atmos. Sci. 31, pp 506–512. models bound the current data and as pp95-106. Matsui, Tamura, 2009. such provide a useful insight into the Church, Snow, Baker, Agee, 1979. Influence of incident flow range velocity data examined herein. Characteristics of tornado-like vortices conditions on generation of as a function of swirl ratio: A laboratory tornado-like flow. EACWE 5, investigation. J. Atmos. Sci. 36, pp 1755–1776. Florence, Italy. Figure 4. Dimensionless tangential velocity component for Davies-Jones, 1973. The Dependence of core Mishra, James, Letchford, different swirl ratios. UK WIND ENGINEERING SOCIETY [ Issue I - 2015 ] 3 2008. Physical simulation of a single-celled tornado-like vortex, Part A: Flow field characterization. J. Wind Eng. Ind. Aerodyn. 96, pp 1243–1257. Mishra, James, Letchford, 2008. Physical simulation of a single-celled tornado-like vortex, Part B: Wind loading on a cubical model. J. Wind Eng. Ind. Aerodyn. 96, pp 1258–1273. Provic, 2013. US Tornadoes, Examining Tornadoes…Past, Present and Future.