dy n ami c s issue 3.02 issue s

issue 3.02 ENGINEERING SUCCESS e ng i n eeri su cc ess.

Features

AEROSPACE SPORT MARINE BUILDING UAV’s Close Formation Flight Bicycle Wheel Aerodynamics Twin Marine Lifter Personal Ventilation Systems contents Introduction 03 Engineering Success Introduction by David L Vaughn 07 13 05 Breaking News • Java™ Hut • Microsoft 07 Wilson Football Simulation - Cover Story 11 STAR-CCM+ & Abaqus FEA co-simulation 13 Power-On-Demand AUTOMOTIVE 15 Suzuki 15 19 Aerodynamics & air-cooling performance 19 Heat Transfer Turning the lights on 23 Le Mans Prototype Increasing Front Downforce 26 Battery Design STAR-CCM+ Battery Simulation Module Aerospace 23 31 27 Close Formation Flight Unmanned aerial vehicles take to the skies SPORT 31 Bicycle Wheel Aerodynamics: Increasing workflow productivity with STAR-CCM+ & FieldView BUILDING SERVICES 35 Feel an Open Window Anywhere Personal air ventilation systems 35 39 INDUSTRIAL & COMMERCIAL APPLICATIONS 39 Flowserve Optimization of Flow Coefficients for Large Control Valves ENERGY 42 Energy Giant Revolutionary wind turbine design 43 A Solar Powered Future 43 45 Qualitative leap in renewable energy with STAR-CCM+ OIL & GAS 45 the Deeper You Go... Improving deep subsea oil & gas drilling performance Marine 49 Extreme Weight Lifting Resistance Calculation for SeaMetric Twin Marine Lifter 53 RANS Simulation 49 53 Complex marine flow problems Regulars 57 Training Global offices DC -adapco 58 Global Events Americas Europe Asia-Pacific Cover Image: Wilson football simulated in STAR-CCM+ (page 22) United States United Kingdom India: CD-adapco Headquarters Headquarters Bangalore CD-adapco • New York office CD-adapco • London office [email protected] 60 Broadhollow Road 200 Shepherds Bush Road Japan: CD-adapco Melville, NY 11747, USA London, W6 7NL, UK Yokohama EDITORIAL Tel.: (+1) 631 549 2300 Tel.: (+44) 20 7471 6200 [email protected] [email protected] [email protected] Dynamics welcomes editorial from all users of CD-adapco software or services. Korea: CD-adapco www.cd-adapco.com www.cd-adapco.com To submit an article email: [email protected] Seoul Telephone: +44 (0)20 7471 6200 Atlanta GA Aberdeen [email protected] Austin TX [email protected] Editor Stephen Ferguson - [email protected] Singapore: CD-adapco SEAsia Cincinnati OH Assistant Editor Deborah Saban - [email protected] France: Lyon, Paris Singapore Detroit MI Associate Editors Prashanth Shankara - [email protected] [email protected] [email protected] Houston TX Lauren Gautier - [email protected] Germany: Nürnberg Lebanon NH Art Direction & Design Brandon Botha - [email protected] [email protected] Los Angeles CA E-Dynamics Chris Dunne - [email protected] Seattle WA Italy: Rome, Turin Advertising Sales Geri Jackman - [email protected] State College PA [email protected] US Events Tara Firenze - [email protected] Tulsa OK Norway: Oslo European Events Sandra Maureder - [email protected] [email protected] [email protected] Subscriptions & DIGITAL EDITIONS For S. America - please contact Dynamics is published approximately twice a year, and distributed internationally. Melville Office RECYCLED PAPER. VEGETABLE INKS. All recent editions of Dynamics, Special Reports & Digital Reports are now available online: http://www.cd-adapco.com/press_room/dynamics We also produce our monthly e-Dynamics which are available on subscription. Resellers Russia Resellers SAROV To subscribe or unsubscribe to Dynamics and e-Dynamics, please email [email protected] Australia China To advertise in Dynamics magazine or e-Dynamics, please download our media kit online: [email protected] Veta Pty CDAJ China www.cd-adapco.com/products/brochures/dynamics/mediakit.pdf South Africa [email protected] Beijing • Shanghai Aerotherm Computational Dynamics IN LOVING MEMORY - THIS ISSUE IS DEDICATED TO IBRAHIM Greece [email protected] [email protected] CD-adapco is mourning the death of Ibrahim Hadžić, a member of the development ENEFEL Japan team in Nuremberg office, who died at the age of 42 on September 27, 2010. [email protected] Turkey CDAJ Japan He has fought a battle against pancreatic and liver cancer since October 2009, A-Ztech Ltd Israel Yokohama • Kobe but unfortunately neither the two surgeries nor the chemo-therapy helped. [email protected] ADCOM [email protected] Ibrahim - whom friends called Ibro - never gave up and worked on his tasks through [email protected] this difficult period until the end of July. New Zealand We will always remember him for who he was: a dedicated scientist, a loyal employee, Matrix Applied Computing Ltd. a great colleague and a good man in every respect... [email protected] ..::INTRODUCTION Engineering Success

We ensure our customers remain successful with engineering services that provide them with facilitated transfer of technology, burst capacity resources and custom software tools.

Engineering Success Introduction by David L Vaughn

CD-adapco’s principal aim is “Engineering Success”: to help our customers to succeed through the application of engineering simulation, driving innovation in their products AND reducing the engineering time and cost associated with bringing those products to market.

In its most fundamental form, success works on a personal level, The articles in this magazine detail just a few examples of the many success ensuring that individual engineers are able to deliver meaningful stories that we encounter every day. I hope that as you read them, you will be simulation results on time and in a manner which can be used to inspired to consider your own application areas, and the ways in which we can influence the design process. help you to be even more successful in the future.

Because CD-adapco was founded by, and is almost entirely staffed by, Enjoy your read. simulation engineers, we are uniquely placed to understand the challenges faced by you every day. Having walked in the same shoes, we understand the importance of ensuring our software products are accurate, efficient and easy to use.

We also recognize that the path to success is not always a smooth one. We David L Vaughn are committed to providing excellent dedicated software support. Engineers VP Worldwide Marketing are tasked with understanding your processes and issues, and are on-hand at CD-adapco any time to ensure that you are using our software in the most effective and efficient way.

We ensure our customers remain successful with engineering services that provide them with facilitated transfer of technology, burst capacity resources and custom software tools.

i FOR MORE INFORMATION PLEASE EMAIL: [email protected]

03 dynamics ISSUE 3.02 Engineering Success ..::INTRODUCTION Breaking News

Welcome to the JAVA™ Hut: a community application exchange for STAR-CCM+

CD-adapco announces JAVA™ Hut, the über-cool way for users to enhance productivity and automate engineering processes with STAR-CCM+.

“It’s a community thing,” says Stephen McIlwain, CD-adapco’s Director have developed for STAR-CCM+ and also download Java™ scripts from other of Support. “We are constantly surprised by the degree of innovation users that they might find helpful in their analyses. CD-adapco also provides that our users bring to STAR-CCM+, often writing macros and scripts that a forum for users to rate the usefulness of the application, provide feedback enhance STAR-CCM+ in ways that we never would have imagined. JAVA™ Hut for the author and suggest possible enhancements. fosters this collaboration and communication among the CD-adapco user “With new developments in technology and social networking, CD-adapco community for those wishing to extend their use of STAR-CCM+ by sharing stays in the forefront of the CAE industry by offering its customers tools and downloading Java™ scripts.” to enhance productivity and to get the most from STAR-CCM+,” explains Using the modern software architecture of Java™, engineers using McIlwain. “It is extremely important that we continue to create new methods STAR-CCM+ in their engineering processes are further enhancing the for our customers to be successful and get even more out of one of the potential of the code by scripting JAVA™ applications that link directly into world’s best CFD codes. JAVA™ Hut is just another way for us to do this.” the STAR-CCM+ suite. The Java™ apps are being used to deeply integrate STAR-CCM+ directly into engineering processes, to provide fully automated JAVA™ Hut is now available for CD-adapco customers to use. CAE simulation suites, extend applicability of the toolset into new areas, and link directly to other CAE tools. The intention of JAVA™ Hut (http://javahut.cd-adapco.com) is to provide i MORE INFORMATION http://javahut.cd-adapco.com a collection point for STAR-CCM+ users to share JAVA™ scripts which they

Release of STAR-CCM+ V5 heralds new strategic partnership for CD-adapco & Microsoft

CD-adapco is strengthening its relationship with Microsoft through tighter support with the Microsoft Operating Systems, Windows 7 and Windows HPC Server 2008, and the integration of STAR-View+ into the Microsoft Office 2010 suite of products.

STAR-CCM+ V5.02 was the first release of CD-adapco’s flagship product to with their simulation models so we’re very excited about the STAR-CCM+ be ported directly onto Microsoft Windows 7, giving the industrial community announcement around Windows 7 and Office 2010.” direct access to multidisciplinary engineering simulation from the comfort STAR-CCM+ allows users to distribute post-processed simulation results as of this new operating system. Joined efforts between the two companies “scene files” containing a three-dimensional representation of the stored CAE are underway to incorporate Windows 7 light-up features in STAR-CCM+. plot. When viewed using STAR-View+, scene files allow the viewer to zoom, For compute-intensive simulations performed over a cluster of Windows pan and rotate the stored model and post-processing data as well as show computers using Windows HPC Server 2008, STAR-CCM+ will be tightly and hide features within the scene. linked to the job scheduling features, compute node management features and image deployment capabilities. Commenting on the strategic partnership, Jean-Claude Ercolanelli, CD-adapco’s VP Product Management, said: “CD-adapco has been working closely together with Microsoft for many years. The releases of Windows 7 and STAR-CCM+ V5 have given us the perfect opportunity to cement this relationship further. The new fruit of our partnership is the direct inclusion of STAR-View+ into Microsoft Office 2007 and MS Office 2010. This enables our users to distribute their simulation results interactively using MS Word, PowerPoint and Excel: enhancing collaboration between engineering teams by giving everyone access to interactive visualization of simulation results.” Greg Kirchoff, Director of Vertical Global ISVs at Microsoft, added, i MORE INFORMATION www.microsoft.com/windows/windows-7 “Engineering customers want desktop applications to work seamlessly

05 dynamics ISSUE 3.02 ..::INTRODUCTION Breaking News

ADVANTAGES OF ENSIGHT CFD Large graphics space, easy to use interface, simple calculator for key computation values, i MORE INFORMATION http://javahut.cd-adapco.com startup wizard to simplify workflow We surveyed the market and found out that you need a better CFD post-processor. Using the same high- quality graphics and rendering engine of EnSight 9, we created a new product specifically tailored to CFD users. The interface is simple and focused, designed to allow you to explore your data interactively. With EnSight CFD, you will be more effective in analyzing, visualizing, and communicating simulation results to your team.

Feature List Read, explore and plot data Add annotations Rotate, pan and zoom Export movies and 3D models Simple calculator Print and save images Create isosurfaces, boundary layers, vortex 32-bit and 64-bit compatible cores, separate/attach lines, and shock Floating and node-locked licenses surfaces Web, email, phone support Create particle traces, transient particle Windows, Mac OS X, Linux compatible traces/pathlines and surface restricted traces Directly import STAR-CD .ccm/.ccmg/.ccmp/.ccmt files

dynamics ISSUE 3.01 www.ensightcfd.co06m ..::INTRODUCTION Wilson Ball Simulation

Advanced Aerodynamics Simulation of Championship Balls Wilson Sporting Goods Co. Teams with CD-adapco

Wilson is taking its soccer balls to the next level in aerodynamics research using CD-adapco’s STAR-CCM+ software on Windows HPC Server 2008.

While the attention of the world focused on soccer balls (or footballs if you prefer) this summer, Wilson continues to drive technical innovation in the design of their sports balls by teaming with CD-adapco to redefine state-of-the-art computer simulation of soccer ball aerodynamics. During preparations and all the way through the final match of this year’s World Cup, FIFA fielded complaints from many players concerned with uncontrollable speed and/or unpredictable flight behavior of the official match ball which was developed and manufactured by the tournament’s primary corporate sponsor. The primary objective of this partnership is to ensure that Wilson maintains its competitive edge in the technical design of its products with a focus on ball aerodynamics. “Wilson has long realized the importance of aerodynamics in the design of reliable and high performance golf balls, footballs, soccer balls, basketballs, and baseballs,” said Doug Guenther, Wilson Sporting Goods Co., Vice President of Research and Development. “Several factors lead to the choice of CD-adapco and STAR-CCM+,” stated Guenther. “The ability of STAR-CCM+ to accurately and efficiently solve unsteady flows with boundary layer transition was certainly a key technical factor, but equally important is the support and flexibility offered by CD-adapco. Their dedicated support model and Power-on-Demand offering is an ideal solution for our needs.” The complexities with computational simulation to analyze the flow around soccer balls are well documented. In the past, most computational fluid dynamics (CFD) studies were limited to fundamental models. g

07 dynamics ISSUE 3.02 ..::INTRODUCTION Wilson Ball Simulation

dynamics ISSUE 3.02 08 ..::INTRODUCTION Wilson Ball Simulation

This was accomplished by simplifying the details in the shape of the ball and ultimately reducing the actual flow physics involved. These simplifications eventually led to inaccurate results, forcing ball designers to perform expensive and time consuming wind tunnel tests. STAR-CCM+ is CD-adapco’s flagship software product which allows engineers to accurately and efficiently simulate aerodynamics (and other types of fluid flow) of any level of complexity using CFD. Using STAR-CCM+ allows Wilson to easily model the genuine shape of the ball including details such as the panels, seams and stitches. This is imperative because these geometric details affect the transition of the airflow from laminar to turbulent, and this is the critical element to accurately predicting the aerodynamic drag and stability of the ball. The initial phases of the project were executed using Power-on-Demand with computer clusters running Windows HPC Server 2008. The Power-on-Demand offering from CD-adapco enables Wilson to take advantage of cloud computing when executing STAR-CCM+ simulations. “Cloud computing is a fantastic cost-effective solution for Wilson, and our Power-on-Demand offering makes it easy to use STAR-CCM+ on the cloud.” said David L. Vaughn, VP Worldwide Marketing for CD-adapco. Vaughn continued, “We are proud to partner with Wilson, not only because of their renowned history of quality products, but because of their innovative vision that includes applying technology to continue providing the best equipment to the world of sports.” Wilson and CD-adapco intend to follow the success of this project with studies focusing on other Wilson Sport categories, including American footballs. <

i FOR MORE INFORMATION ON WILSON, PLEASE VISIT www.wilson.com/

09 dynamics ISSUE 3.02 ..::INTRODUCTION Wilson Ball Simulation

About CD-adapco CD-adapco is the world’s largest independent CFD focused CAE provider. Our core products are the technology-leading simulation packages, STAR-CCM+ and STAR-CD. The scope of activities, however, extends well beyond CFD software development to encompass a wide range of CAE engineering services in fluid dynamics, heat transfer and structural engineering with an ongoing mission to “inspire innovation and reduce costs through the application of engineering simulation software and services.” A privately owned company, CD-adapco has maintained 16% organic year-on-year growth over the last 5 years. CD-adapco employs over 400 talented individuals, working at 21 different offices across the globe.

About Wilson Chicago-based Wilson Sporting Goods Co., a division of Amer Sports, is one of the world’s leading manufacturers of sports equipment. The company designs, manufactures and distributes advanced equipment that helps players improve their performance. Wilson’s core categories include Baseball, Football, Basketball, Softball, Bats, Volleyball, Soccer, Youth Sports, Uniforms/Apparel, Golf, Footwear, and Racquet Sports (Tennis, Racquetball, Squash, Badminton and Platform Tennis).

Wilson has long realized the importance of aerodynamics in the design of reliable and high performance golf balls, footballs, soccer balls, basketballs, and baseballs. Doug Guenther, Wilson Sporting Goods Co. Vice President of Research & Development

dynamics ISSUE 3.02 10 ..::INTRODUCTION STAR-CCM+ & Abaqus FEA

SIMULIA is the Dassault Systémes brand that delivers a scalable portfolio of Realistic Simulation solutions. This includes the Abaqus product suite for Unified Finite Element Analysis, multiphysics solutions for insight into challenging engineering problems, and SIMULIA SLM for managing simulation data, processes, and intellectual property. By building on established technology, respected quality, and superior customer service, SIMULIA makes realistic simulation an integral business practice that improves product performance, reduces physical prototypes, and drives innovation. Headquartered in Providence, RI, USA, SIMULIA provides sales, services, and support through a global network of regional offices and distributors. www.simulia.com

ABOVE Co-simulation is the most practical and accurate method of solving aerodynamic flutter problems STAR-CCM+ & Abaqus FEA co-simulation makes seamless fluid-structure interaction a reality

By working closely with SIMULIA, we have managed to create a tool that, for the first time, brings best-in-class coupled fluid-structure interaction within the reach of a typical engineer. CD-adapco Senior VP of Operations, Dr. Bill Clark

i MORE INFORMATION VISIT www.cd-adapco.com/press_room

11 dynamics ISSUE 3.02 ..::INTRODUCTION STAR-CCM+ & Abaqus FEA

CD-adapco is pleased to announce that its industry leading simulation tool, STAR-CCM+, now includes a direct link to Abaqus FEA from SIMULIA, delivering fully coupled, two-way, fluid-structure interaction (FSI).

From the bending of a tree’s branch in the wind to the flutter of an aircraft wing CD-adapco’s partnership with SIMULIA also means that setting up and running as it crosses the Atlantic, fluids and solids interact in harmony everywhere the problem may all be done within the easy-to-use STAR-CCM+ environment, in the real world. However, in the virtual world of engineering simulation, with no need for writing scripts and input files or mapping data. Simply the picture has rarely been quite so harmonious. Structural analysis and point STAR-CCM+ at the Abaqus FEA job you want to run and press “Go.” fluid dynamics, although intrinsically linked, have long been quite separate The powerful physics of both codes may be leveraged in coupled FSI with disciplines with the interaction between deforming structures and flowing STAR-CCM+’s full range of available models, providing the ability to study fluids only being considered at a most basic level. coupled, single and multiphase flows, chemical reaction and combustion as The first products available for FSI simulations were often prohibitively well as flow regimes from low speed to hypersonic. The options available expensive, in terms of computer resources and timescales, and relied upon in Abaqus are similarly broad, with coupled simulation supported for third-party inter-code communication that had to be specifically configured static stress/displacement, dynamics (implicit and explicit), heat transfer, for each new scenario. For these reasons, the numerical simulation of temperature-displacement, thermal-electrical and piezoelectric analysis. FSI problems has traditionally been the preserve of research projects and Put simply, the close-coupling between STAR-CCM+ and Abaqus brings academic studies, operating outside of the main engineering design process. the solution of a wide range of FSI problems within the easy reach of a typical Not anymore. For the first time, CD-adapco’s industry leading simulation engineer. In terms of both practicality and accuracy, co-simulation (in which tool, STAR-CCM+, will have a direct link to Abaqus FEA, delivering fully both codes exchange data as they simultaneously run) is the only way to coupled, two-way, fluid-structure interaction. Using direct co-simulation tackle problems such as aerodynamic flutter, fluid induced bending, vortex coupling provides efficiency and reduced overhead associated with things induced vibration and galloping. < such as data transfer through file exchanges or use of external middleware software. This will make coupled fluid-structure-thermal calculations a regular part of the engineering design process. “This direct co-simulation coupling is possible because of the strong BELOW partnership between CD-adapco and SIMULIA,” said CD-adapco Senior Abaqus FEA and STAR-CCM+ co-simulation can be used to solve problems such as tire aquaplaning. VP of Operations Dr. Bill Clark. “By working closely with SIMULIA, we have managed to create a tool that, for the first time, brings best-in-class coupled fluid-structure interaction within the reach of a typical engineer.” “Our partnership with CD-adapco is a key part of our commitment to provide our mutual customers with a coupled multiphysics solution that helps them gain deeper understanding of their products’ real-world product behavior earlier in their development cycle,” stated Steve Levine, Chief Strategy Officer, SIMULIA, Dassault Systèmes. “SIMULIA is committed to developing new and improved direct co-simulation solutions that enable our valued partners such as CD-adapco to help their customers reduce time and costs of delivering high quality products to market.”

dynamics ISSUE 3.02 12 ..::INTRODUCTION Power-On-Demand

The compelling benefits of STAR-CCM+ / Power-on-Demand include: Increased Power: Each license allows access to unlimited computing resources, either on your own cluster or using those of cloud computing services Increased Throughput: Each license allows to run an uncounted number of sessions, concurrently or not Increased Flexibility: Creation of a flexible simulation environment that expands and contracts based on your workload and target performance parameters, providing you with burst capacity Power-on-Demand: Engineering Simulation in the Cloud In the past thirty years, engineering simulation has evolved beyond all recognition. Once a speculative “Research and Development Tool,” simulation now plays a constant and critical role in almost any product development, generating a constant stream of engineering data that leads the design process. Once the sole domain of PhD-qualified academics, today’s simulations are as likely to be carried out by application engineers and designers as they are by simulation specialists.

13 dynamics ISSUE 3.02 ..::INTRODUCTION Power-On-Demand

Perhaps most importantly of all, everyone now has access to Burst Capacity “super-computer” technology. Even the most humble of laptops With little prospect of being allowed to purchase a new super-computer every now contain a multi-core processor, while serious engineering time demand temporarily increased, users were usually stuck with a fixed simulations can routinely use hundreds, if not thousands, of number of “software seats,” independent of demand. This often posed some computer cores at a time. Using client-server software, an engineer can, with difficult problems: a simple laptop, monitor the results of an engineering simulation running on What happens if your company suddenly wins an unexpectedly large short hundreds of cores on a computer cluster than might be physically located on term contract that will push your current simulation capacity beyond its limit? a different continent. What happens in the weeks before a design freeze, when the whole However, when it comes to the licensing of simulation software, the more engineering department is frantically demanding simulation data, and spare things change, the more they stay the same. Since the very start, users of computer processors and unused software licenses are rarer than gold dust? Computer Aided Engineering (CAE) software have been bound by inflexible What happens, a few weeks later, during vacation time, when demand for annual licensing schemes that take no account of the cyclical nature of simulation results is down, and computers and software licenses lie idle? simulation demand experienced by a typical enterprise. Each year, users were What has been missing from the traditional license model is a “burst forced to buy a certain number of “seats” (the number of instances of the capacity” allowing users to scale up their software usage during busy periods software that can be run at one time) and limited to a set number of computer and then scale it back down as necessary. With this in mind, in April 2010, processors that could be run simultaneously. During times of peak demand, CD-adapco introduced a Real Time Licensing scheme for their flagship users were forced to fight over the same software and hardware resources that STAR-CCM+ engineering simulation tool. often remained unused during less busy times. Until recently, the number of software licenses that a company Real Time Licensing purchased was determined almost entirely by the extent of the hardware The “Power-on-Demand” license allows users to access unlimited computational resources to which they had access. Users purchased (or long term resources for a single hourly fixed fee, breaking the relationship between license leased) an expensive mainframe computer, with as many processors cost and computer resources (number of cores) used for a simulation. Rather and as much memory as they could afford, and then simply bought a than purchasing STAR-CCM+ licenses “by the seat” or “by the processor,” big enough software license to keep that computer number crunching Power-on-Demand allows users to purchase licenses “by the hour.” for as many hours a week as possible. If the simulation workload outgrew For example, a five hundred hour license would allow you to run as many the number-crunching ability of the machine, the only option would be to simulations as you could set up, using as many processors as you have access purchase a new, bigger computer and additional software licenses to match. to, for a period of up to five hundred hours. Hours are purchased in blocks, using an online account, and are immediately available for the user to deploy as and when they are needed. Unused hours are credited back to the users account to be used at a later date. A bulk discount is applied to purchases, so the more hours a user buys, the lower the cost per hour. Power-on-Demand license scheme provides users with a flexible simulation environment that expands and contracts based on workload. This could be used either as a “burst capacity,” to allow users with a traditional annual license to top up their simulation capability at times of peak demand (allowing them to reduce the size of their annual licenses to mean demand level), or to provide an on-demand capability for occasional users.

Cloud Computing Each license allows you to access unlimited computing resources, either on your own cluster or using those of cloud computing services such as Amazon EC2 and SGI Cyclone (or any other public or private cloud), giving users immediate access to almost unlimited computing resources without having to worry about infrastructure or security issues. The latest versions of STAR-CCM+ are available on both Amazon EC2 and SGI Cyclone, so the user need only download the light-weight STAR-CCM+ client on their local machine (usually a standard laptop), purchase some hours, and begin the simulation. Although we do not anticipate that our users will immediately begin to run all of their simulations on the cloud, in the few weeks after the Power-on- Demand scheme was released, CD-adapco was inundated with requests from our existing customers, all of whom were keen to embrace a more flexible approach to engineering simulation. < i FOR AN ONLINE VERSION OF THIS ARTICLE, VISIT: www.cd-adapco.com/press_room/2010/31-03-cloud.html

dynamics ISSUE 3.02 14 ..::FEATURE ARTICLE Automotive

Simultaneous Evaluation on Aerodynamics & Air-Cooling Performances for Motorcycle using CFD Analysis

Yoshihiko Sunayama, Ph.D - Group Leader, CAE Group, Digital Engineering Dept. Suzuki Motor Corporation

In the development of a sports motorcycle, a balance must be achieved between low drag to improve performance and good airflow through the cooling system to maintain

reasonable fuel economy. Typically, however, a low drag coefficient (CD) and increased flow through the heat exchangers are contradictory in nature, as an improvement in one leads to deterioration in the other. With this in mind, Suzuki looked to STAR-CCM+ to help optimize their bike designs by studying aerodynamics and heat exchanger flow simultaneously.

In order to develop a set of best practices for future analyses, a study of the the coarse grid and around 24 millions cells for the fine one. The k-ε realizable influence of turbulence models and mesh density on motorbike performance and k-ω SST turbulence models were also studied. was performed. STAR-CCM+ was used and, for validation purposes, its results A suitably sized computational domain is key to the accurate, and were compared with wind tunnel measurements on a test vehicle. therefore successful, analysis of vehicle external aerodynamics (of any configuration). Consequently, a rectangular box 8 times the width, 5 times Computational & Experimental Methods the height and 6 times the length of the bike was used as our simulation Two mesh sizes---coarse and fine---were considered for this study, both domain to ensure that the boundaries had no detrimental effect on the flow consisting predominantly of hexahedral (trimmed) cells and polyhedral cells field near the motorbike. With the external boundaries in place, a blockage in the heat exchangers. Both meshes were generated automatically with ratio of just 1.6% was achieved. In order to assess the accuracy of the STAR-CCM+ and volumetric refinements were used to better capture flow computational results, the values of CD and of the flow velocity through the heat structures around the bike in general and through the heat exchangers exchangers were measured in the wind tunnel with vane-type anemometers specifically. The resulting mesh consisted of approximately 17 millions cells for attached at 16 different locations on the back face of the radiator. g

❐ FACTS

Boasting an all-new compact engine, shorter wheelbase and new styling, the new GSX-R1000 raises the bar once more in the hotly-contested Supersport class. With significant changes in the engine department, the new GSX-R features a more over-square bore and stroke, larger, titanium valves, a higher compression ratio, and 12 hole fuel injectors, to deliver a finer fuel mist for more complete combustion. All this with a power-plant that is 59mm shorter from front to rear. And it’s not just the engine that’s seen the significant changes either, as the all-new chassis makes the GSX-R1000 more agile than ever before. With a unique engine and chassis package, the aggressive aesthetics and rider controls top-off the flagship GSX-R. With the unique Suzuki Advanced Exhaust System, featuring low-slung MotoGP inspired titanium exhausts, a lighter, sculptured fuel tank, on-board lap timer and revised Suzuki Drive Mode Selector controls, the new bike offers the complete sports package. Suzuki GSX-R1000 2009.

15 dynamics ISSUE 3.02 ..::FEATURE ARTICLE Automotive

Creativity - a human gift to develop products that promote better living conditions and satisfy people’s need. Since the founding of Suzuki Motor Corporation, we have always pursued providing ‘value-packed products’ as one of our manufacturing philosophies. Realizing that the value differs according to the times, country and lifestyle, we are fully determined to challenge for the creativity to make such products for customers around the world with our advanced technologies and enthusiasm.

N disc, twin disc, disc 220mm caliper, 1-piston tubeless (58W) ZR17M/C 120/70 tubeless (73W) ZR17M/C 190/50 preload fully adjustable, rebound and and rebound adjustable, fully preload compression damping force fully adjustable fully force damping compression mm 310 calipers, 4-piston mount, Radial preload fully adjustable, rebound and and rebound adjustable, fully preload compression damping force fully adjustable fully force damping compression spring spring, coil damped, oil type, Link Inverted telescopic, coil spring, spring spring spring, coil telescopic, Inverted IO T

Rear brakes: Rear tyres: Front tyres: Rear

Front brakes: Front

Rear suspension: Rear Front suspension: Front CHASSIS SPECIFICA CHASSIS S N 999cc Four stroke, liquid-cooled, DOHC liquid-cooled, stroke, Four mm 57.3 x mm 74.5 1 : 12.8 sump Wet Electronic ignition (Transistorised) ignition Electronic injection Fuel Electric mesh constant 6-speed Chain IO T

E SPECIFICA E

N GI N Engine capacity: Engine Engine: E Bore: ratio: Compression Lubrication: Ignition: Fuel system: Fuel Starter: Transmission: Drive: S S N IO T S T 17.5litres (3.8 UK gallons) UK (3.8 17.5litres 2045mm (80.5in) 2045mm (28in) 710mm (44.5in) 1130mm (55.3in) 1405mm (31.9in) 810mm (447.5lbs) 203kg -R1000 2009 SPECIFICA 2009 -R1000 X

S & WEIGH & S

GS N ki SIO u N z FACTS IME Overall width: Overall height: Overall Wheelbase: height: Seat Mass: Kerb capacity: Fuel D length: Overall Su ❐

i MORE INFORMATION ON SUZUKI GSX-R1000 2009: www.suzuki-gb.co.uk/bike/gsxr1000k9/tech/

dynamics ISSUE 3.02 16 ..::FEATURE ARTICLE Automotive

ABOVE Type A: fine mesh

ABOVE ABOVE Pressure Distribution Type B: coarse mesh

Drag analysis to the overall drag is the cowling, responsible for approximately a quarter The experimental and computational results of CD were compared. Cases 1 of the total drag. The radiator produces the second higher drag component, and 2 are the results of the SST k-ω model with the mesh of type A (fine) and representing 13.4% of the total. These observations only highlight the B (coarse) respectively, while Cases 3 and 4 are the results of the realizable importance of optimizing the radiator flow to minimize the drag while k-ε model with, again, the mesh of type A and B respectively. Across all maintaining the cooling performance. mesh/turbulence model comparisons, the maximum difference between the For this analysis, the accuracy of STAR-CCM+’ predictions turned out experimental and the computational results was found to be 2.9%. to be more than acceptable, making STAR-CCM+ a reference design tool for When comparing turbulence models on a same mesh, the values of CD for future bike applications, providing that an adequately fine mesh and the the SST k-ω were 0.017 to 0.019 higher than those given by the realizable k-ε correct turbulence model are used. model. When comparing mesh sizes for a given turbulence model, the values of CD for the finer mesh were found to be 0.010 to 0.012 higher than those Radiator flow obtained with the coarse mesh. The experimental and computational results of the radiator mean flow velocity In Case 1, the total drag force of the test vehicle was broken down into the were compared for both mesh sizes and turbulence models. Velocities were contributions of its different part. This showed that the largest contributor found to be overpredicted by 8.1 to 16.8% compared to experimental

(a) C1 C2 C3 C4

R1 1.42 1.00 1.02 1.11

R2 1.16 0.83 0.98 0.99

R3 0.89 0.99 0.91 0.86

R4 1.24 1.66 1.45 1.29

(b) C1 C2 C3 C4

R1 1.34 0.96 1.07 1.14

R2 1.34 0.99 0.91 1.19

R3 0.99 1.22 1.27 1.12

R4 1.26 1.43 1.71 1.43

Table 1 Velocity distribution of flow passing through radiator in (a) Case 1 and (b) Case 3, normalized by experimental velocity.

17 dynamics ISSUE 3.02 ..::FEATURE ARTICLE Automotive

Suzuki GSX-R1000 2009.

ABOVE ABOVE Velocity field around the central section of the motorbike Oil cooler measurements, with the best agreement reached when using the k-ε SST model - although the results quality showed a higher mesh dependency than with the k-ε turbulence model. To study the flow velocity distribution through the radiator, the velocity was calculated at four different locations, C1, C2, C3 and C4. The results, normalized by the experimental velocity, are shown in Table 1. It can be seen that the best agreement with experiment, for both Cases 1 & 3, is reached in the upper central region of the radiator at points C2 & C3, where high velocities are reached as the bulk flow goes straight through the radiator, between the front forks, tire and cowling. This good agreement between computational and experimental results in the higher velocity regions of the radiator is likely due to the “simpler” nature of the flow field there. The flow in the other areas of the radiator is relatively difficult to model and simulate properly as it includes shear flows from the front forks and flows almost parallel to the frontal surface of the radiator.

Conclusion In order to assess both the aerodynamics and air-cooling performances of a motorcycle in a single simulation, a set of best practices has had to be developed and validated. The conclusions obtained from this study are as follows: • An excellent match (less than 3% difference) was found between STAR-CCM+’ predictions and wind-tunnel measurements of CD, giving us the confidence to use STAR-CCM+ for drag evaluation of motorcycles. • A good match (less than 10% difference) was found between STAR-CCM+’ predictions and wind-tunnel measurements of the flow mean velocity throughthe radiator. This shows that although STAR-CCM+’ results are accurate enough for the assessment of air-cooling performance of motorcycles, there is still scope for improvement in the accuracy of STAR-CCM+’ predictions. • The results obtained with the SST k-ω turbulence model showed a higher sensitivity to the mesh size; however using this model in combination with ABOVE a fine grid led to more accurate results than when using the realizable Radiator k-ε turbulence model. < dynamics ISSUE 3.02 18 ..::FEATURE ARTICLE Automotive

ABOVE ABOVE ABOVE Numerical results for the simple prototype Thermography for the simple prototype Example internal flow of a rear lamp

RIGHT Example bulb temperature

AMET is a high-tech engineering company, active in the design and development of mechanic and mechatronic products and processes based on numerical simulation.

Olsa supplies worldwide components for interior and exterior lighting for vehicles. In order to produce the best products, Olsa R&D laboratory uses the most innovative and modern solutions.

19 dynamics ISSUE 3.02 ..::FEATURE ARTICLE Automotive

Turning on the light on heat transfer Flavio Cimolin, AMET S.r.l, Andrea Menotti, Olsa S.p,A, Lucia Sclafani, CD-adapco

The design of rear lamps for the automotive industry is becoming more challenging as an ever finer compromise between product lightness and resistance to heat loads needs to be found. Only after engineers have successfully achieved this delicate but essential balance, style and aesthetics considerations can be added to the equation.

OLSA, supplier of interior and exterior lighting components for In order to be approved for use on an automobile, a newly developed the worldwide automotive industry, and AMET, an engineering rear lamp must pass a series of physical tests designed to represent company that specializes in the design and development of the most testing thermal conditions that the lamp is expected to face in products and processes using numerical simulation, have developed a operation (including combinations of heat, rain, wind or moisture loads). complete methodology for the thermo-mechanical simulation of a lamp. The use of simulation from the earliest stages of the design process This comprehensive model tracks the exchange of convective and radiative can help to significantly decrease the probability of failing these tests, thermal energy from the filament of the lamp, and includes transparency greatly reducing both costs and development time. effects from the bulb as well as interactions with other components in the assembly. The approach has been successfully validated by experimental Setting up the model comparison with a simple prototype of a lamp, with results from STAR-CCM+ An automotive lamp can be seen as a complex thermo-mechanical system showing good qualitative agreement and perfect energy balances. in which the stresses acting on the components depend strongly on the heat transfers between them. The principle source of thermal energy is The challenge the filament, which can easily reach temperatures of 3500°C or more, and When designing an automotive lamp, accurately predicting its thermal emits radiative energy. behaviour is essential: intense heat loads can cause severe plastic Part of this radiation is absorbed by the transparent bulb, which reaches deformations of both the body and the external lens, possibly resulting in a temperature of 400-600°C, and therefore becomes a significant source of global damage to the whole optical component. radiation in its own right. Using the STAR-CCM+ surface-to-surface radiation This is a significant problem when considering today’s stylish designs model and a Kirchhoff model of transparency, the model reproduces the which demand the use of thinner and lighter materials (often deployed fundamental mechanisms of radiative heat transfer. in unconventional geometric configurations). Although radiation is the dominant heat transfer mechanism, the influence of natural convection is also significant as the large temperature differences between the bulb and the main body of the lamp drive the recirculation of the air inside the lamp, resulting in “hot-spots” such as the one directly above the bulb. A typical rear lamp model - including solid meshes of multiple bulbs and other optical or screening-related components, as well as the internal air volume - requires a mesh size of at least 500,000 cells. If external air is considered, the number of cells can exceeds 3 million, leading to several hours of multi-processor computation for a steady state simulation. g

❐ FACTS Headlights are one of the most highly regulated systems on any automobile. The first vehicle headlamps were officially introduced during the 1880s and were based on acetylene and oil, similar to the old gaslamps. The first electric headlamp was produced by the Electric Vehicle Company based in Hartford, CT in 1898. Until 1975, all US headlights had to be round, non-halogen, DOT-approved sealed beam units with 2 large dual-beam bulbs or 4 ABOVE Mesh of the rear lamp small single-beam bulbs which gave no room for stylish headlights.

i FOR MORE INFORMATION ON OLSA VISIT: www.olsa.it

dynamics ISSUE 3.02 20 ..::FEATURE ARTICLE Automotive

ABOVE ABOVE Geometry of the simple prototype Heat extraction by the oven

Validation and verification the heat transfer associated with natural convection has a significant The verification and validation of the approach have been assessed by influence on the overall thermal field. means of both theoretical considerations and experimental investigations. In addition, unsteady simulations are essential in the case of complex When considering simple geometries, the radiative heat transfer multi-bulb lamps, where the tests are performed by turning on and off between the filament, the bulb and the body of the lamp can be directly different lights at different scheduled times. The application of a standard computed by means of Stephan-Boltzmann law together with energy unsteady simulation would currently require a very large amount of computing conservation. This approach shows perfect agreement between the resources. However, a smart alternation of the solvers associated to energy numerical and the theoretical results. Even when considering a very and flow (by means of the “Freeze Flow” and “Freeze Energy” options) complex lamp configuration in external air, the energy balance between the results in a dramatic CPU time reduction, making this apparently unfeasible power dissipated from the filament(s) and that exiting the system is well simulation possible using available computer resources. captured by the numerical model. In order to perform a thorough validation of the methodology, a cubic Conclusions prototype of a lamp was considered and investigated experimentally by This new STAR-CCM+-based CFD methodology for the thermo-mechanical means of infrared thermal camera images and thermocouples. The simulation of optical devices has proved to be robust and capable, and numerical simulations of the cubic box in external air showed fairly good has helped design thermo-mechanical aesthetically pleasing lights with agreement with the experimental measurements, with an overall error durable, high-quality, all-weather performance. Furthermore, deploying less than 5% on the body of the box. These comparisons are necessary simulation early in the design process has enabled a significant reduction in order to correctly calibrate the important physical parameters in the amount of physical testing required to bring products to market.< of the model, such as the emissivity, reflectivity and transmissivity coefficients on different surfaces, or to exactly calculate the heat transfer coefficient of the external boundary of the lamp.

Advanced issues Thorough investigations of the type described above lead to a confident applicability of this numerical methodology to increasingly complex (and increasingly realistic) geometries. However, the secondary but nonetheless important issue of lamp ventilation and natural convection also requires consideration, as highlighted by the so-called “ventilated oven test”. Another important issue to deal with is the case of open lamps, in which

i FOR MORE INFORMATION ON AMET VISIT: www.amet.it

21 dynamics ISSUE 3.02 ..::FEATURE ARTICLE Automotive

ABOVE Internal temperature

ABOVE Geometry of the automotive rear-light

ABOVE Centerline plane temperature and velocity field inside domain for the simple prototype

dynamics ISSUE 3.02 22 ..::FEATURE ARTICLE Automotive

Le Mans Prototype: Increasing Front Downforce Jean-Philippe Pélaprat - ORECA, France

23 dynamics ISSUE 3.02 ..::FEATURE ARTICLE Automotive

ABOVE ABOVE Coefficient of pressure on the bodywork and flaps (front view) Coefficient of pressure on the bodywork and flaps (side view) The aerodynamic configuration of a Le Mans Prototype depends on the nature of the track where it races: some pre-installed parts may be adjusted, such as the rear wing main plane or the flap. Regulations permit the homologation of various versions of the aerodynamic package but place restrictions on how many changes can be made. Typically, up to two “flaps” are allowed to be added on the front fenders in order to increase the front downforce. These flaps are the object of the aero analysis and optimization described in the article.

The ORECA Group has been a leading contender in RIGHT motor racing for 35 years. Oreca competes in Le Mans Iso-surface of Q-Criterion Series and 24 hrs of Le Mans with his own prototype, and also in World Touring Car Championship for Seat Motorsport. Two departments are concentrated on business/marketing operations: the sale of equipment and accessories, and the Special Event Department for marketing and incentive operations. www.oreca.fr/UK

Oreca and CFD The aerodynamic requirements for these different types of track are obviously Oreca started to work with CFD software at the beginning of 2009 and, after very different. Therefore, the ability to analyze different configurations rapidly is evaluating different packages, it was found that STAR-CCM+ offered the best needed. The fast tracks necessitate a reduction in drag and an improvement compromise in terms of ease of use and accuracy. Our first aim was to get a in aerodynamic efficiency, while on slow tracks the focus is on increasing the better understanding of Le Mans Prototype (LMP) aerodynamics as well as a overall downforce. Apart from optimizing the levels of aerodynamic drag and good support for wind tunnel testing. Moreover, CFD enabled us to develop the downforce, some other aspects of race car aerodynamics such as aerodynamic aero-package throughout the season thereby reducing our dependence on wind balance or ride height sensitivity need to be studied. tunnel testing. Simulation Properties Aero-configurations At Oreca, only “full-vehicle” simulations are carried out, as the addition of flaps LMP cars are designed to compete in LMS (Le Mans Series), ALMS (American at the front of the car can significantly alter the air flow under the car and into Le Mans Series), Asian Le Mans Series and, of course, the 24 Hours of Le the rear diffuser. The k-Omega SST turbulence model was used in conjunction Mans. The tracks used for these Championships have different characteristics. with a trimmed hexahedral mesh, and prismatic layers were added on the car’s On the fastest track, the top speed is over 320kph, the average speed is surface to help resolve the flow inside the boundary layer, thereby increasing the around 230kph and the straights represent 80% of the track. On the slowest accuracy of the results. The floor was set up as a “moving wall”, with its tangential track, the top speed is only 290kph, the average speed is around 175kph and velocity being equal to the inlet velocity, while boundary conditions at the wheels the straights represent 60% of the track. and brake discs were chosen to account for their rotational velocities. g

dynamics ISSUE 3.02 24 ..::FEATURE ARTICLE Automotive

Dive-Plane

Splitter Side-Panel

ABOVE ABOVE Configuration 1 Configuration 2

ABOVE ABOVE Trimmer mesh of the bodywork Configuration 2 (top view)

Geometry tested Dive-Plane Base Dble On the front of the car, the rules and regulations permit the addition of up to two + Endplate “flaps”. The “flaps” can be considered as either a dive-plane or a splitter end SCX - 5,28% 9.50% plate. The Baseline was a standard HDF (High Down-Force) configuration chosen after the wind-tunnel tests results, with double small dive-planes, which is a CAR SCZ - 4.27% 8.03% good configuration in terms of efficiency. FRONT BALANCE - 3.75% 4.15% The target was to design new parts which would increase the total level of downforce, switch the aero-balance to the front and keep the same level of aerodynamic efficiency. Two other double dive-plane configurations were tested, the first with bigger parts and the second with splitter endplates combined with a dive-plane.

Results For both configurations, parameters such as height and angle of attack were varied to find an optimal design. Furthermore, in order to assess the differences between the various new components, visualization of the pressure coefficient (CP), wall-shear stress and Q-criterion were compared. Using a force report, we could check the impact of each part of the dive-plane ABOVE and splitter side panel. It was easy to see, for example, whether the effect of Close-up of the dive plane the side-panel would modify the underbody air flow or act only under the splitter. As a final result of this aerodynamic analysis, we found that the double dive-plane is the best compromise in terms of downforce, balance and aerodynamic efficiency. With a new aerodynamic package developed with STAR-CCM+, Team ORECA Matmut AIM competed at the prestigious 2009 24 Hours of Le Mans race. The aerodynamic advances achieved during this optimization process made strong running possible during one of the most famous races in the world. <

RIGHT (courtesy ORECA Racing) Le Mans in its genes! ORECA has been a constructor since the end of 2007, and it has already made a name for itself with the ORECA 01 racing in LM P1, and the Formula Le Mans prototypes. The Signes-based Group has used the experience gained with these two cars to build the ORECA 03. This new prototype will be on sale for teams wanting to race in 2011 in the Le Mans 24 Hours and in the different Le Mans Series in the LM P2 category.

i FOR MORE INFORMATION ON ORECA VISIT: www.oreca.fr

25 dynamics ISSUE 3.02 ..::FEATURE ARTICLE Battery

LEFT Streamlines of cooling air flow around discharging battery cells MIDDLE Maximum predicted battery cell temperatures for different discharge rates RIGHT Screen shot of a 30KWh battery pack colored by battery cell temperature STAR-CCM+ Battery Simulation Module Since our collaboration was announced last year, the development teams of both CD-adapco and Battery Design LLC have been working hard to bring this exciting project to fruition. The principal objective of the project is to deliver a tool that will allow Dive-Plane Base Dble engineers to simulate flow, thermal and electrochemistry within a single code. + Endplate SCX - 5,28% 9.50% Achieving this goal required our multidisciplinary team to information about the internal cell quantities. These battery models are overcome numerous hurdles; as well as the fundamental solver dependent on the surrounding thermal conditions which will influence their CAR SCZ - 4.27% 8.03% enhancements required to provide the pioneering simulation, electrical performance during the analysis. By solving both thermal and electro- the upstream pre-processing of battery geometry and input data was also chemistry quantities within one solution, a design engineer can instantly see FRONT BALANCE - 3.75% 4.15% a major task. This article expands on some of the details of the technology the impact of a specific installation upon a given cell’s performance. and looks at the use of software from the point of view of a battery engineer. This allows installation designs to be compared, for example to judge the maximum non-uniformity of temperature across a module of battery cells, Setting up the Analysis facilitating design decisions. Since the same core battery cell behavior is “Where do I start?” is a common question we encounter when discussing maintained, different simulations can easily be compared. the input requirements for battery simulation. Of course, an understanding The Battery Simulation Module provides simulation data for the battery of the electrical and thermal performance of a battery under relevant test cell that shows the internal gradients created by the location of current conditions is required to ‘characterize’ the battery and hence its response to carrying tabs and the applied cooling strategy. Within large format lithium the simulated conditions predicted. This upstream work is completed using ion batteries, those used in traction applications, controlling these internal the ‘Battery Design Studio’ package, which builds a characterization from gradients, whether thermal or electrical, is the key to obtaining long life from battery discharge curves and other associated data. Geometry information a particular battery pack. Visualizing these gradients as part of a larger of the battery and surrounding components is also required, the former being simulation provides invaluable data to battery engineers. automatically generated by STAR-CCM+, with the latter imported from CAD packages or created using STAR-CCM+ 3D-CAD. Post Processing As battery modules and packs tend to be constructed from a series Having computed what potentially could be a large transient simulation, of identical cells and conducting or structural components, STAR-CCM+’s the engineer can now extract data concerning the thermal and electrical Battery Simulation Module provides tools to copy out an assembly to quickly performance of this simulated battery pack. The graph above shows output create a module or pack. This expedites the creation of the simulation model from monitoring the temperature of a battery cell during a range of discharge and allows battery engineers to create fictional packs, as well as respecting conditions. Understanding the temperature at which a cooling system’s physical designs, exploring ‘what if’ cooling scenarios and design changes. performance matches a cell’s heat generation is crucial to controlling cell temperature. This is a typical scenario and the Battery Simulation Module The Solver Strategy allows an engineer to achieve the optimum engineering solution from a given As already discussed, the pioneering solver computes flow, thermal and set of spatial and performance constraints. electrochemistry quantities within a single solution. The solver can handle all The Battery Simulation Module is available in STAR-CCM+ 6.02 as an forms of battery cooling from free convection, through forced air convection additional add-on. up to liquid or refrigerant cooling. The interface allows users to choose the battery model solver, ranging from equivalent circuit models - whereby the response of the battery to an electrical load is modeled using a simplified i FOR MORE INFORMATION: [email protected] circuit model - to a more complex electrochemistry model - providing detailed

dynamics ISSUE 3.02 26 ..::FEATURE ARTICLE Aerospace

BELOW Vertical component of the velocity field around UAV1 and UAV2 shown in a xy-plane located right above the wing upper surface

UAVs in Close Formation Flight

Deborah Saban, Technical Marketing Engineer, CD-adapco.

ABOVE Spanwise component of the velocity field around UAV1 and UAV2 shown in a xy-plane located right above the wing upper surface

27 dynamics ISSUE 3.02 ..::FEATURE ARTICLE Aerospace

ABOVE Tangential velocity field behind UAV2

The last decade has seen an increased interest in the development of Unmanned Aerial Vehicles (UAVs) and their applications which are no longer restricted to the military field of operations. UAVs - either remotely piloted or fully autonomous - provide a safer, cheaper alternative to larger, piloted aircraft, as well as a valuable ‘bird’s eye’ observation platform mid-way between ground-based sensors and high-flying satellites.

These considerations have opened the way to UAV applications in The entire simulation process, from pre-processing to post-processing, is many other fields, such as homeland security (police surveillance, performed using CD-adapco’s flagship software, STAR-CCM+. STAR-CCM+’s border patrol, etc.), public services (fire fighting, search and rescue, high level of automation enables the user to focus on engineering data analysis power-line and pipeline inspections, chemical and pollution sensing, climate rather than on time-consuming repetitive tasks, as demonstrated through the monitoring, etc.), and the commercial sector (geographic surveys, aerial following steps:

communications networks, crop spraying, etc.), and made them the choice of 1. The airframe geometry of one Pusher UAV, UAV1, is imported predilection to perform the ‘3D’ (Dirty, Dull and Dangerous) missions. and automatically cleaned up and prepared for meshing: STAR-CCM+’s However, as some missions – such as air-to-air refueling, weapons surface wrapping feature enables any imported geometry, regardless of reloading, aerial launch & recovery or aerial surveillance – require multiple its complexity and initial quality, to be covered by a clean ‘second skin’ vehicle close formation deployments, a detailed understanding of the wake surface mesh. vortex effects caused by one vehicle upon another is needed. This optional operation can be performed within a few minutes using This article aims at demonstrating how the CFD software, STAR-CCM+, can STAR-CCM+, thereby sparing the CAD and CFD engineer of long and dull be used to investigate the nature of dynamic air vehicle interactive coupling and hours (if not days) of surface repairing where each individual cell needs to its consequences during close formation flights. A formation of two identical be addressed independently. tailless pushers, UAV1 and UAV2, is considered for these purposes. Both 2. UAV2 is generated by simply copying and pasting UAV1 to the desired vehicles are flying at the same level in a station keeping scenario and the follower location. This operation can be repeated each time a UAV needs to be added to is located 0.9 wingspan behind and 0.9 wingspan starboard of the leader. the formation. g

ABOVE Vorticity magnitude behind UAV1

dynamics ISSUE 3.02 28 ..::FEATURE ARTICLE Aerospace

RIGHT Geese flying ‘V Formation’

3. A large boundary volume enclosing UAV1 and UAV2 is then chosen and meshed, using either tetrahedral, polyhedral, or trimmed (hexahedral) cells. The use of polyhedral meshing, which is another of STAR-CCM+’s innovative features, can provide the same accuracy as a typical tetrahedral mesh with at least 5 times fewer cells. Once again, STAR-CCM+ enhances productivity and efficiency without compromising the accuracy of the solution.

This trick has not been invented by CFD engineers: geese and ducks have 4. Several levels of mesh refinement are set up through the use of volumetric been using it in their migration V-formation shapes since the beginning of time. controls in order to fully capture UAV1’s wake and its effects on UAV2. However, STAR-CCM+’s colorful post-processing tools enable the CFD engineer

to demonstrate it in a more artistic way than ever before. Not just Art for Art’s 5. The properties of the physics continuum are then defined, including the sake though. STAR-CCM+, with its fast, powerful and user-friendly all-in-one model to be used, its reference values and initial conditions. integrated environment, proves to be the ideal platform to assess the benefits, as well as the risks and issues, associated with wake vortex evolution and STAR-CCM+ is now ready to perform the computation, at the end of which encounter, thereby providing the enabling science on which the development the solution can easily be analysed using STAR-CCM+’s colorful and powerful of new procedures and protocols for UAV close formation deployments may be post-processing tools. securely based. < The post-processing results clearly show how the upwash, downwash and sidewash generated outboard and inboard of UAV1’s wing tips can affect UAV2’s stability. They confirm the well-known fact that wake vortices represent severe atmospheric disturbances which can be, depending on the relative positions of the air vehicles in the formation, either beneficial or detrimental, not to mention dangerous. Dangerous because of the strong and sometimes unexpected rolling moment that can be induced on a wake-encountering vehicle by such a concentrated core of vorticity. Beneficial because if the follower positions itself in the up-current generated by the leader, the induced drag of the trailing aircraft is dramatically reduced, leading to significant fuel savings and/or an increased range with a given payload. This translates into real economic and environ- mental benefits, which are certainly not to be overlooked in a time when the emphasis is set on developing newer, greener and cheaper technologies.

RIGHT Tangential velocity field behind UAV2

STAR-CCM+ Product Features

Single Integrated Process Automatic Meshing Technology Turbulence STAR-CCM+’s unique simulation process delivers unrivaled Advanced automatic polyhedral or hexahedral meshing With its extensive selection of turbulence models, ease-of-use and automation to accurate, engineering CFD. gives the ultimate combination of speed, control and STAR-CCM+ is guaranteed to meet your requirements. accuracy. CAD Embedding Post-processing Powerful CFD from within your chosen CAD package: Additional Physics Modeling From contours plots, to XY-graphs and streamlines to SolidWorks, Pro/E, CATIA V5 or Unigraphics NX. The fastest developing solution in CFD, STAR-CCM+ is animations. Extract Engineering insight with STAR-CCM+. equipped with a comprehensive selection of physics Surface Wrapping Software and Hardware Technology models. Accurate solutions in an easy-to-use environment. Spending hours or days cleaning CAD or preparing a Client-server architecture, object-oriented programming surface mesh? The Surface Wrapper will cut this time to and unrivaled parallel performance, STAR-CCM+ uniquely minutes. utilises the latest technology.

i VISIT OUR NEW AEROSPACE HUB: www.cd-adapco.com/applications/aerospace

29 dynamics ISSUE 3.02 ..::FEATURE ARTICLE Aerospace

dynamics ISSUE 3.02 30 ..::FEATURE ARTICLE Sport

Increasing Workflow Productivity with TS AR-CCM+ & FieldView

By Matthew N. Godo, Ph.D., FieldView product manager, Intelligent Light

Aerodynamics: In the world of CFD simulation, maximizing return on investment comes not

just from reducing the cost of analysis while increasing output, but from fully mining that output for critical insight and accurate answers. STAR-CCM+ and STAR-CD users are well aware of the many benefits these powerful and popular solver codes bring to the design and engineering process, including the ability to solve complex, large data problems. If analyzing that data can’t be done efficiently and effectively, however, the investment in those resources won’t be fully realized.

A high productivity CFD workflow is imperative, physical wind tunnel testing has significant limitations. Making both economically and competitively, for exploring direct comparisons between test results from different facilities

Wheel multiple designs and complex phenomena within tight is problematic; contributions to drag cannot be separated out by

design cycles. As we found in a recent study at Intelligent Light, individual component; vertical forces acting toward or away from post-processing results with FieldView™ harnesses the value of the floor cannot be calculated because the wheel is usually affixed STAR-CCM+ and STAR-CD solution data and speeds the search for to forks; and not least, wind tunnel testing is expensive and time answers, demonstrating both the need for and the value of robust, intensive. With today’s sophisticated CFD software and high automated post-processing. performance computing resources, we saw an opportunity to put CFD simulation to the test by developing a comprehensive, flexible Bicycle Wheel Aerodynamics methodology to model and analyze bicycle wheels. Studying the aerodynamic flow around a rotating bicycle wheel Using STAR-CCM+ and FieldView, we studied multiple in contact with the ground, including the front fork and frame wheels and fork/frame combinations at two speeds and components, presents a unique CFD challenge. Wind tunnel testing 10 different yaw angles totaling 120 cases. The surface has been used extensively for two decades to study and reduce wrapping capability of STAR-CCM+ was tremendously helpful drag in cycling applications, resulting in significant improvements in setting up the problems and generating the meshes of in equipment and an enhanced awareness of aerodynamics. But each wheel design, handling the detailed geometry well. g

i FOR MORE INFORMATION ABOUT THIS STORY PLEASE VISIT: www.ilight.com/wheel Bicycle

31 dynamics ISSUE 3.02 ..::FEATURE ARTICLE Sport

Technology, Teamwork, Trust For over 25 years, Intelligent Light has been helping customers find the answers to their most challenging problems. Intelligent Light delivers the world’s most advanced technologies for understanding and visualizing large complex data. The FieldView family of products delivers a comprehensive CFD post-processing suite that supports people in mission critical CFD environments. Our long partnership with CD-adapco was born from our shared commitment to meeting the demanding needs of these customers. Industry leaders rely daily on Intelligent Light’s staff for products, consulting, research, and support to make their CFD jobs accurate, fast and easy. Visit us at: www.ilight.com to learn more and experience FieldView for free. www.ilight.com

RIGHT Massless particles called ‘streamlines’ were released from a set of fixed circumferential positions, resulting in highly detailed animations of the air flow. On the suction side we can see that at low yaw, strong recirculation is observed at the top, outer edge of wheel, with weaker recirculation seen at the bottom half, inner edge of wheel. As yaw angle increases, top recirculation extends along front of wheel and combines with inner wheel recirculation. The streamlines and images were created automatically using FieldView FVX routines.

dynamics ISSUE 3.02 32 ..::FEATURE ARTICLE Sport

ABOVE Zipp 404 (left); Zipp 1080 (right) In this image, as the flow is drawn into a slotted fork, it can be seen pulling away from the wheel rim and tire. At higher yaw angles, the flow gets trapped behind the fork, and strong recirculation pulls the flow upward.

STAR-CCM+ showed excellent parallel scaling on the complex geometry, making computing this many cases feasible. The tight interface between the two products provided a seamless transfer of FV-UNS files, and by leveraging FieldView’s automation and visualization capabilities, just a few hours of upfront system design resulted in a highly productive workflow that was repeatedly put to the test as the study progressed and new data was added. Meeting research and publication deadlines would have been impossible without the combined strengths of STAR-CCM+ and FieldView. The study’s findings - that drag force does depend on the wheel and is influenced by the choice of the front fork, and that the wheel rim and tire, not the hub and spokes, dominate the overall drag-challenges conventional wisdom and opens up new avenues of exploration for bicycle wheel manufacturers and the cycling industry in general.

Robust, reliable automation speeds the workflow During the steady simulations, approximately 3.6 gigabytes of data were generated, while the unsteady simulations resulted in nearly 1.2 terabytes of data. In the past, this quantity of data, its complexity, and the repetitive nature of the calculations would have posed a seemingly insurmountable challenge for researchers. FieldView is particularly well suited to handling transient cases, and we used FieldView’s FVX™ programming language to automate many post-processing tasks, including: • resolving the forces on the wheel into their drag, side, and vertical components; • breaking the resolved forces down to those acting on each component: wheel rim and tire, hub, spokes, and fork; • calculating the resolved forces along the wheel circumference; • creating custom visualizations of flow structures for standardized quantitative and qualitative evaluation. For ease of use, we specifically developed automation routines that were geometry-independent and applicable to both steady or transient simulations with few or no changes. An automated workflow must be robust and reliable, ABOVE The surface wrapping capability of STAR-CCM+ delivered high-quality meshes on detailed geometry inherently stable and yet flexible in order to evolve and capture best practices. and allowed the control to maintain surface density on different components.

33 dynamics ISSUE 3.02 ..::FEATURE ARTICLE Sport ZIPP 404

LEFT Resolved forces around the wheel perimeter were averaged on small t t t t t t t t DIRECTION OF FLOW t t t t t t t t circular arc segments for each yaw angle and plotted as a function of the wheel circumference. The tools in FieldView enabled this unique representation of data. ZIPP 1080

NO FORK REYNOLDS CARBON BLACKWELL BANDIT

Because FieldView is always 100% backward compatible, these routines can be Parallel, batch options fully utilize STAR-CCM+ and HPC investment used without modification with future releases of FieldView. FieldView maximizes existing hardware and solver/software resources in both In each instance, tasks that would have taken many weeks to accomplish concurrent and scalable operations. Intelligent Light’s exclusive batch-only in a traditional, serial workflow were completed in days. After the initial time licensing option can cut costs by up to 90% versus individual interactive licenses, invested in writing the routines, we used them extensively - for example, the while parallel processing can be used to reduce post-processing time on single same FieldView FVX routine was run 60 times to calculate the drag force for all simulations. wheel and fork combinations at two speeds. Some tasks, such as calculating Post-processing the large volume of data in the bicycle wheel study was circumferential variation, which entailed 3600 calculations for each wheel and significantly accelerated by STAR-CCM+’s high quality multi-grid export to fork combination, would simply not have been possible without automation. FieldView Parallel from the transient datasets. Running FieldView Parallel on eight processors accelerated the work by a factor of five. FieldView FVX routines Advanced, customizable visualization provides insight allowed the automated workflow and custom visualizations to be produced in The larger and more complex a dataset, the more critical it is to be able to quickly batch mode without user intervention. and accurately analyze and understand the results. The advanced visualization Batch-only licensing also meant we could post-process, assemble, and capabilities of FieldView were put to maximum use in the bicycle wheel study, interpret multiple cases and time steps concurrently, while keeping the resulting in unique, unprecedented views of flow features, circumferential STAR-CCM+ solver running at the same time to generate additional solution data. variations, and helicity. Performing post-processing while solutions were being generated, and without Two surprises - an unexpected vertical force transition and previously having to move data off the server due to FieldView’s client-server operation, unseen, highly resolved flow structures - were brought to virtual life by the greatly increased the research team’s work capacity and saved significant time. tools and capabilities of FieldView. A method available within FieldView called ‘streamlines’ was used to release massless particles from a set of High productivity CFD wins the race fixed circumferential positions (created by a simple FieldView FVX routine), For bicycle wheel manufacturers and designers, the findings of this study offer resulting in highly detailed animations depicting the flow across the wheel new and intriguing avenues of exploration in the quest for competitive advantage. and fork. Good agreement with experimental wind tunnel studies suggests that the Much more than just ‘pretty pictures’, these illustrations and animations methodology we developed holds considerable promises for future research. provided rare insight into the wheel’s aerodynamic performance. The research Overall, the study provides compelling evidence that CFD simulation can team was able, in essence, to ‘sit’ on the edge of the wheel and ride through its indeed be used to tackle problems and questions previously considered too rotations, capturing and visualizing, for the first time, the complex interactions complex to be easily solved. The power of the STAR-CCM+ solver and the happening unseen with every turn of the wheel. automation and visualization capabilities of FieldView combined to create a highly productive, fast and efficient workflow that maximizes every resource - software, hardware, people, and time - and sets the stage for future discoveries. < i FOR MORE INFORMATION ABOUT USING FIELDVIEW WITH STAR SOLVERS, PLEASE VISIT: www.ilight.com/cd-adapco

dynamics ISSUE 3.02 34 ..::FEATURE ARTICLE Building Services

Propulsive Wing, LLC was formed in 2006 to commercialize a newly-developed high-lift, high-payload flying wing platform. Instead RIGHT of external propellers, the design utilizes Streamlines with Personal Breeze turned on partially-embedded cross-flow fans for thrust and boundary-layer control. Based on 6 years of research and development, the aircraft is readily scalable and reconfigurable to meet specific mission requirements.

35 dynamics ISSUE 3.02 ..::FEATURE ARTICLE Building Services

Feel an Open Window Anywhere Personal Breeze Air Purifier Joseph Kummer and JB Allred, Propulsive Wing LLC

Airborne allergens and contaminants found in public places have been proven to have an adverse effect on people, such as a reduced productivity at the workplace, an increased exposure to diseases on airplanes, unhealthy learning environments for children, and sometimes the occurrence of secondary infections in hospitals. One potential solution is the use of personal air ventilation systems, or PAVs.

As the problem of poor indoor air quality reaches near epidemic levels (to the extent that certain environments are said to suffer from “Sick Building Syndrome”) and with people spending the vast majority of their time indoor, a solution needs to be found to help the millions of people who suffer due to transmitted disease and allergic reactions to airborne pollutants. Large, bulky, floor air purifiers are generally effective in small to medium rooms but tend to be noisy, expensive, and to consume large amounts of energy. Furthermore, in an open office setting, due to the large room volume and high airflow mixing, these units have only a minor impact on overall air quality. At the other end of the spectrum, small wearable air purifiers typically do not remove contaminants well, and many release ozone as a bi-product of the filtration process, which is itself a pollutant. With funding from the Syracuse Center of Excellence and U.S. Environmental Protection Agency, Propulsive Wing LLC, in collaboration with Allred & Associates Inc. and Syracuse University, has developed the Personal Breeze Air Purifier System, a revolutionary personal air purifier that reduces contaminant and allergen exposure, delivering clean, fresh air to an individual. This methodology, which utilizes the individual’s self generated thermal plume to enhance cleaning effectiveness, is compact, quiet, and consumes only 2 watts. By attaching the Personal Breeze to the front of a desk or to the tray table on an airplane, the user enjoys a light, refreshing breeze of filtered air. Instead of allowing allergens to flow freely up to the breathing zone, the contaminated airstream is diverted, filtered, and then re-injected back into the natural thermal plume. This type of personal air purification provides filtered air to the user for only a fraction of the power consumption and noise of other products. In “breeze” mode, the air purifier simulates the natural fluctuations of real wind: it feels like there is an open window near you, wherever you happen to be. The engineering simulation tool STAR-CCM+ was used to design and develop the Personal Breeze Air Purifier. Simulations were performed of a person working at a desk, onto which the PAV device has been attached. The PAV draws in air from the occupant’s thermal plume, filters it, and blows out a stream of clean air under the person’s chin. Both the external (around the person) and internal (inside the ducting) airflows were modeled and simulated, and the results were used to optimize the air purifier configuration. A number of cases were simulated with the Personal Breeze both off and on. In order to reduce the grid count, simplify the calculations and enable parametric studies, the rotating cross-flow fan of the Personal Breeze was modeled using a simple velocity inlet; this enabled the simulations to be run in steady state g 36 ..::FEATURE ARTICLE Building Services

Testing of Personal Breeze in Indoor Air Quality Chamber at Syracuse University using Personal Breeze attached to desk and plugged into laptop computer via USB port Thermal Manikin

Velocity magnitude contours with Personal Breeze fan on Velocity magnitude contours with Personal Breeze fan off

mode, thereby significantly reducing the simulation time. The grid was were investigated to optimize both the power requirements and the refined near the person, the laptop computer, and in proximity of the dimensions of the PAV. In addition to being an effective filtration air purifier in order to correctly resolve the behaviors of the exhaust solution, the Personal Breeze was designed to be convenient to use jet and of the flow in the thermal plume. When the purifier is turned in an office setting: the unit interfaces with a computer for power, off, the thermal plumes rising from the person and the computer are control, and performance monitoring. clearly visible: STAR-CCM+ results show that the air breathed by the Finally, in order to assess and validate the effectiveness of the person originates from the floor, and moves up through the region Personal Breeze system, prototypes were tested in the Building at the front of the desk - where the PAV is optimally located - before Energy and Environmental Systems Laboratory at Syracuse University. reaching the breathing zone. Compared with the ambient air, a reduction of up to 60% in particle When the Personal Breeze is turned on, most of the air which contaminant levels in the breathing zone was demonstrated. The reaches the breathing zone is filtered. Parametric studies were final design was proved to meet all specifications, including power performed to evaluate the effect of the outlet flow velocity and angle consumption smaller than 2.5 watts, Windows-based control, in order to optimize the effectiveness of the device and minimize its rechargeable battery for portability, on-board environmental sensors power consumption. One important characteristic of the Personal Breeze system is that the direction of the natural air flow is only very and easy filter replacement. slightly altered; therefore, the energy input needed by the PAV is Without STAR-CCM+, this would not have been possible within considerably reduced compared with a system which aims at signifi- the time-frame of the 1-year grant period. Follow-on designs currently cantly changing the flow patterns. in development will add heating and cooling, humidification and Internal aerodynamic studies regarding the flow path within the dehumidification, and several other features, with the objective to air purifier were also performed. In particular, the relationships provide a complete personal environmental solution for the office between fan size and speed, filter type, and filter and duct geometries worker and the traveler. <

i FOR MORE INFORMATION ON PROPULSIVE WING PLEASE VISIT: www.propulsivewing.com

37 dynamics ISSUE 3.02 ..::FEATURE ARTICLE Building Services

BELOW BELOW RIGHT Meshed model of a man working at a desk with a laptop Streamlines with Personal Breeze turned off computer and a Personal Breeze Air Purifier

dynamics ISSUE 3.02 38 ..::FEATURE ARTICLE Flow Control

Mark Eight Control Valve

Features: • Straight-through flow allows higher Cv per given size over globe style valves • Less restriction through seat permits less line turbulence • Interchangeable part with other Mark series valves for less inventory • Accurate, high thrust cylinder actuator to shut off against high pressure drops

39 dynamics ISSUE 3.02 ..::FEATURE ARTICLE Flow Control FLOWSERVE STAR-CCM+ Enables the Optimization of Flow Coefficients for Large Control Valves

Gifford Z. Decker, FLOWSERVE - Flow Control Division.

Flowserve is the recognized world leader in supplying pumps, valves, seals, automation and services to the power, oil, gas, chemical, and other industries. With more than 14,000 employees in more than 56 countries, we combine our global reach with a local presence.

ABOVE CAD geometry rendering The increasing demand for accurate values of the flow capacity coefficient (Cv) for large and non-standard control valves (i.e. those with a diameter of 12 inches or more) has made Computational Fluid Dynamics an extremely valuable tool to reduce the potential high costs and development time associated with flow-testing. For Flowserve, Flow Control Division (FCD), CD-adapco’s flagship engineering simulation software STAR-CCM+ has provided that capability.

Efficiency and lead time in the population of Cv values for RIGHT Streamlines through valve non-standard and large size control valves can be improved by eliminating flow testing and using CFD to generate accurate values of the Cv. Through the positive outcome of a series of tests, Flowserve FCD has successfully demonstrated how STAR-CCM+ can be trusted to provide customers with highly reliable Cv values for the design and optimization of large control valves. be modeled. The models were meshed using polyhedral cells and the mesh The Challenge was locally refined near the throat of the valve in order to capture the high This article describes the set-up, results and conclusions of the analysis of a velocity gradients. The fluid physics were then defined using a steady state 20-inch Y-body valve whose required Cv value exceeds previous conservative turbulent flow model, and standard pressure and temperature were used estimates of flow capacity. Instead of conducting iterative experimental tests to simulate the conditions prescribed by the testing standard ISA-75.02.01 until a satisfactory design solution is achieved (which would have been very “Control Valve Capacity Test Procedures”. expensive and time consuming), STAR-CCM+ was used to optimize the valve The boundary conditions were set as stagnation pressure inlet, pressure trim parts and obtain the desired Cv value. A validation test was eventually outlet, and symmetry on the symmetry face. The Cv was computed using run to ensure that the optimized valve actually meets the Cv requirement. a user-defined field function, and for each case, the simulation was run until Cv’s convergence was reached. By keeping the same parameters Setup from one simulation to another and simply using the “replace surface” The valve models were created using SolidWorks and imported in STAR-CCM+. function to automatically import and test successive valve geometries, The flow being internal and symmetric, only half the fluid domain needed to the time needed to reach convergence was significantly reduced.g

dynamics ISSUE 3.02 40 ..::FEATURE ARTICLE Marine

BELOW Geometry with applied mesh Results STAR-CCM+ was used to adapt the design of a large and non-standard Y-body valve so that it would meet the specified Cv’s requirement. The fluid flow was simulated with STAR-CCM+ for successive geometries of the valve until the predicted flow capacity coefficient would be high enough. The corresponding geometry was built and sent to a large flow capacity testing laboratory where the valve was tested. The results showed that STAR-CCM+ predictions of Cv matched the experimental measurements within 1%. Further helpful information was collected from STAR-CCM+’s final model, such as: • the pressure distribution in the trim exit holes, • the distance from the trim exit holes to the point of pressure recovery, and • the flow field though the valve. This information can be used to continuously improve the design and functionality of Flowserve’s valves and ensure that they are the most reliable and suitable for customer’s applications.

Conclusion CD-adapco’s simulation tool STAR-CCM+ was used to optimize the design of the internal trim of a 20-inch Y-body valve in order to increase its flow capacity to a specified value. Using STAR-CCM+ rather than experimental flow-testing led to a significant reduction in the cost and amount of time required from the design stage to manufacturing and final testing, thereby enabling on-time delivery. The close match between flow-test measurements of the flow capacity coefficient and STAR-CCM+’s predictions increased the level of confidence ABOVE Pressure distribution in trim exit holes in STAR-CCM+, making it the reference tool for future similar valve applications.<

❐ RECORDS WORLD’S BIGGEST VALVE The biggest valve in operation was constructed by the Lined Valve Co. in 2009 in the United States measures an incredible 34 feet tall, 11 feet wide and weighs 52,000 pounds. It was constructed from wood and fitted to a 96-inch storm and waste water drainage system in Chicago.

ABOVE Flow field visualization

Flowserve VALVES The Flowserve Mark Eight control valve is designed with a unique Y style globe body that provides higher flow capacities and less process turbulence than conventional globe valves. Because of its nearly straight through flow passage, the Y style body is less flow restrictive than a normal globe-style body. This permits less pressure to be converted into velocity as the fluid passes through the seat, resulting in a lower valve recovery factor and higher capacity. Mark Eights straight-through design generates less valve and piping turbulence which significantly reduces harmful noise and vibration levels. Like Flowserves Mark One globe valve, the Mark Eight features streamlined, constant area flow passages, top-entry trim, a four-way positioner, and a high thrust cylinder actuator. The Mark Eight is completely interchangeable with the Mark One except for the body, seat retainer, bonnet, and plug. The packing box, actuator, seat ring, flanges, and gaskets are all standard, off-the-shelf items for fast delivery and minimal parts inventory.

i FOR MORE INFORMATION ON FLOWSERVE PLEASE VISIT: www.flowserve.com

41 dynamics ISSUE 3.02 ..::FEATURE ARTICLE Renewable

ABOVE Windgiant WG 600 wind turbines in action with a height of 42 or 56 metres ENERGY GIANT and a turbine diameter of 22 metres CD-adapco helps Windgiant to bring Revolutionary Wind Turbine Design to Market

Stephen Ferguson, CD-adapco. In order to meet the world’s energy demands in a sustainable manner, engineers need to deliver robust innovative technology. For 30 years, CD-adapco has enabled energy engineers to do just that in the ‘traditional’ energy sectors, and is now routinely applying the same advanced engineering simulation technology to the renewable energy sector.

The Windgiant turbine is based on a revolutionary prototypes,” said Gerhard Wieser, the designer and innovator technology, in which wind flow is accelerated through behind the Windgiant project. a multi-bladed fan using a number of concentric “Having successfully installed a number of Windgiant aerodynamic shrouds. Compared with traditional three bladed turbines, I am delighted to report that the devices’ behavior is as turbine designs, the compact Windgiant turbine delivers a much predicted by the simulations, with each device delivering plentiful

higher energy per unit surface area and operates at much lower supplies of low-cost electricity in complex urban environments.” Wingiant are widely wind speeds (delivering energy at wind speeds as small as Dennis Nagy, CD-adapco’s Vice President of Business considered to be ‘the next 1.5 m/s). Combined with its ultra-low noise energy production Development and Director, Energy Industries, concluded: generation of wind turbine design and construction’. (less than 40 dB (A) at 12 meters), the compact design of the “In order to maximize their efficiency, most current wind They are a German based Windgiant turbine means that it is suitable for installation in urban turbines were designed using extensive experimental model organization providing residential settings, as well as industrial environments. Currently testing. Although experimental analysis provides considerable specialized design and construction of small 10kW available in 10kW and 20kW, Windgiant is developing a much insight into the performance of a particular design, physical turbines to super sized larger hybrid-tower which delivers 2.5MW from a combination of prototypes are expensive and time consuming to construct. 600kW giant wind turbines, wind and solar power. Engineering Simulation allows the designers of innovative as well as the design and construction of wind parks “CD-adapco’s Engineering Services team helped us to concepts such as the Windgiant turbine to demonstrate their with 6 or more giant wind demonstrate that our concept was valid, and allowed us to feasibility without committing unnecessary expenditure to the turbines. fine-tune our design before investing in expensive physical construction of prototypes.” <

i FOR MORE INFORMATION ON WINDGIANT PLEASE VISIT: www.windgiant.com

dynamics ISSUE 3.02 42 ..::FEATURE ARTICLE Renewable

RIGHT Aerial view of a PV panel installation on a factory deck

Prosolia was founded in 2003 in Ontinyent (Valencia,Spain) with the aim of developing environment-friendly energy systems based on solar energy and non-polluting natural resources. With a staff comprising of more than 80 highly-qualified and experienced professionals in the solar energy field, we offer an integral turnkey service to our custumers. Our commitment to the environment and society is evidenced by our sustainable and cost effective systems, as well as our participation in research firms, our sports and cultural sponsorship and our partnership with NGOs. A Solar Powered Future Qualitative Leap in Renewable Energy with STAR-CCM+

Juan Antonio Carrio - Prosolia. In 2008, Prosolia Solar Energy responded to the maturity of the Renewable Energy sector in Spain by undertaking the development of photovoltaic (PV) panels with increased efficiency. STAR-CCM+, CD-adapco’s flagship software, was chosen to assist us in this challenging task. Introducing STAR-CCM+ to our company allowed our Engineering and R&D&I departments to unfold a range of new capabilities by translating the engineering simulation expertise acquired by CD-adapco throughout the years to Prosolia’s world of renewable and clean energy.

i FOR MORE INFORMATION ON PROSOLIA PLEASE VISIT: www.prosolia.com

43 dynamics ISSUE 3.02 ..::FEATURE ARTICLE Renewable

ABOVE ABOVE View of the space between the panel and the roof (10 cm) with prism Flow field and thermal variation on the panels layers to solve the turbulent flow

Renewable energy and CFD determines the power output of the panel, the thermal behavior of the PV panels Incorporation CFD into our engineering department was not an easy decision was also examined. A simulation of the flow field around, and thermal variations for our company. To be worthwhile, the cost of implementing CFD had to be on the panels enabled the immediate improvement of the configuration’s design, compensated by: so that maximum cooling could be achieved from the airflow under the panels. • a reduction in assembly costs, Solar radiation was then added to the model. Determining the effects of • an increase of the level of engineering expertise offered to our customers, and solar radiation on the panels is a competitive advantage in the renewable • an improved ability to generate alternative designs. energy sector, so using STAR-CCM+ turned out to be a valuable asset for us. The absorption of incident solar radiation by the panels could be accurately The initial step in the implementation of STAR-CCM+ was to validate its calculated, leading to major improvements in temperature control by convection numerical predictions against experimental data using simple models. The and radiation. To obtain the structural load and thermal parameters of each satisfactory output of the validation process enabled a ‘best practice’ protocol panel, the free stream velocity was set to 30 m/s and the solar radiation to to be generated for more complex applications. about 1000 W/m2. All this information is essential to improve a given design, to create new Principle support systems for PV plates with plastic components and to adequately adapt The fundamental premise on which Prosolia relies for PV panel design can be load levels to conventional structures. By helping us to better understand heat summarized as follows: “A photovoltaic panel is an element that, if correctly transfer phenomena, STAR-CCM+ has enabled us to develop solar thermal installed, does not interfere with its environment and, in turn, generates the systems with improved photovoltaic efficiency, and has become an essential maximum possible energy from solar radiation”. This requires the knowledge of tool for Prosolia’s R&D&I department. structural loads, primarily the effect of the wind on the panels. Different panel configurations were simulated in STAR-CCM+ to determine the Results most thermally efficient design. The best configuration, based on“the inclination STAR-CCM+’s predictions of pressure and suction areas for different configu- producing the most energy at affordable loads”, was then built and tested. rations were compared and the design of the deck was optimized accordingly. Qualitative Leap in Renewable Energy with STAR-CCM+ To increase the energy production, the photovoltaic panels were tilted by an angle Design and simulation based on the simulations’ results. The turbulent flow was properly resolved and The use of CFD as a tool to design a photovoltaic system is something new. Both the changes in structural loads well predicted, with numerical results in good global and local thermal effects on the panels are important to ensure that the agreement with ‘real-life’ temperatures monitored on a PV installation. air flows smoothly through the entire system. First, the original CAD model was simplified and imported into STAR-CCM+ Conclusions (the effect of these simplifications on the solution was verified to be insignificant Knowing the flow field around the panels can help the engineer to optimally a posteriori). Various panel configurations were then added to the factory design the installation. STAR-CCM+’s thermal simulations’ results showed deck. In order to reach the best compromise between accuracy of the results that the cell temperature reduction is directly proportional to the volume of and computational costs, the computational domain was reduced to a 2D air flowing between the deck and the PV panels; in other words, an increase environment and the mesh was locally refined near the panels using volume in the distance between these elements causes an increase in the energy controls. STAR-CCM+’s automated meshing feature was then used to create a dissipation both by convection and radiation. With the help of STAR-CCM+, a trimmed cell mesh. streamlined design process could be established and optimized photovoltaic Secondly, the effects of the wind were assessed. To get the most appropriate panels with an increased ratio of energy output over Wp installed could be panel setting for the given load profile, these were simulated in an empty deck successfully designed. < scenario as well as for different panel configurations. As the cell temperature

dynamics ISSUE 3.02 44 ..::FEATURE ARTICLE Oil & Gas

Baker Hughes Incorporated (NYSE: BHI) provides reliable, practical solutions when and where our customers need them to lower costs, reduce risk and improve productivity. From the reservoir to the refinery we create value with high-performance products and services to analyze, drill, evaluate, complete and produce oil and gas reserves and then transport and refine the hydrocarbons. For over a century, innovation has been part of our DNA. Baker Hughes was formed in 1986 with the merger of Baker International and Hughes Tool Company, both founded over 100 years ago when R.C. Baker and Howard Hughes conceived ground-breaking inventions that revolutionized the fledgling petroleum era. Since those earliest advancements, we’ve never stopped searching for solutions to conquer the next frontier. The Deeper You Go... The Less You Know Simulation Demonstrates Ability to Improve Deep Subsea Oil & Gas Drilling Performance

Dennis Nagy, Vice President, Business Development - CD-adapco

45 dynamics ISSUE 3.02 ..::FEATURE ARTICLE Oil & Gas

RIGHT Streamlines around the drill bit

The key to successful implementation of CFD in drill bit hydraulics is the ability to correlate the CFD results to actual down hole performance of the drill bits Dr. Michael Wells, Director of Research, Baker Hughes

The ongoing push for more producible oil and gas reservoirs is leading the industry into greater offshore depths and harsher environments. The challenge of developing and producing from fields at depths up to 25,000 feet requires workers to operate unproven technology in harsher environments, including greater ambient pressure, lower temperature and different well fluid temperatures, pressures and compositions.

Traditional design approaches to developing equipment and have from 3 to 12 blades emanating from the center of the bit outwards. systems for shallower offshore wells often don’t work effectively Embedded in these blades are polycrystalline diamond cutters (PDC) which in these deeper, harsher environments. Further, the nature of consist of thin diamond wafers attached to carbide backings. The cutters are drilling makes it very difficult to diagnose the performance of down hole laid out to ensure that the entire bottom of the hole is cut while promoting (in the wellbore) equipment in the field. How can petroleum and marine bit stability. mechanical engineers move outside their traditional realm of experience to The region between the blades, called the junk slots, provides a path for develop new designs that will improve drilling performance in these new the removal of rock cuttings. Commonly, a single nozzle is positioned at the challenging environments? top of each blade that feeds high velocity liquid (drilling mud) through the junk To address these difficulties, oil and gas companies and their suppliers slot to clear loose rock debris from beneath the bit. Various nozzle configu- are increasingly using computational fluid dynamics (CFD) simulation rations are possible. Bits are designed with multiple nozzles in a junk slot, to optimize the performance of drilling equipment. CFD simulation a single nozzle feeding two junk slots and with no nozzle at all in a junk slot. offers the advantages of providing extensive diagnostic information Dr. Wells indicated that the first step in constructing simulations of down such as the ability to visualize flows and pressures around the bit under hole drilling involves the creation of a full, detailed solid model of the bit and actual drilling conditions. Simulation also makes it possible to quickly the sides and bottom of the hole. The region modeled is a sealed volume and easily evaluate the relative performance of different designs. element comprising the space occupied by the drilling fluid between the bit Dr. Michael Wells, Director of Research for the Hughes Christensen and the hole walls and bottom. A realistic bottom hole pattern, created as division of Baker Hughes and one of the industry’s foremost experts on though generated by the cutters on the bit, is incorporated into the model simulation in oil and gas applications, provides here some examples of and the bit is displaced into the rock (hole bottom) by an amount typical for how simulation is helping to address a variety of drilling challenges. the geological region under consideration. The solid modeling environment is also used to generate text information, Optimizing PCD drill bits blade locations, cutter face centers, nozzle centers and other information Dr. Wells has spent a considerable amount of effort in hydraulic optimi- that is later used by the CFD model. Realistic operational parameters such zation of polycrystalline diamond compact (PDC) drill bits. PDC bits typically as flow rate, nozzle size, rpm and fluid density (mud weight) representativeg

dynamics ISSUE 3.02 46 ..::FEATURE ARTICLE Oil & Gas

ABOVE Figure-8 nozzle used in roller cone drill bit set new field record of 45 feet per hour (fph) compared to previous best of 40 fph (Saudi Aramco).

of the region or application being studied are also incorporated into the model. into STAR-CCM+. The process began by performing experiments using a single The goal of the simulation is typically to size, locate and orient the bit fluid jet to impinge particles on mild steel and carbide matrix (bit materials) nozzles to maximize cuttings transport and minimize erosion. Dr. Wells has specimens. The tests were designed to measure the erosion coefficient, developed an optimization process that involves configuring the hydraulics defined as the ratio of the grams of material eroded from the specimen surface across the bit so that the percentage of the total flow rate that passes through per grams of erodent material impinged on the surface. a particular junk slot is roughly equal to the percentage of the total cuttings Dr. Wells has successfully applied this model in wide variety applications. volume generated by the adjacent blade. Typically the designer used these predictions to move and orient the bit nozzles “The key to successful implementation of CFD in drill bit hydraulics is the to minimize the rate of erosion on the bit surface. While erosion cannot be ability to correlate the CFD results to actual down hole performance of the entirely removed it can be greatly reduced and often directed to less critical drill bits,” Dr. Wells said. Hughes Christensen uses a drilling simulator to tie features of the bit. computed results to actual drilling performance in a controlled environment under representative drilling conditions. The high pressure drilling simulator Optimizing nozzle exit geometry employs actual drill bits (up to 12-1/4 inch in diameter), under realistic pressures Dr. Wells has also used CFD to investigate the effects of the nozzle profile and (up to 15,000 psi) drilling actual rock cores to evaluate drilling efficiency and exit geometry on the efficiency of the drilling process. He numerically analyzed the transport of rock cuttings. Rock cores commonly used are Mancos Shale, the flow produced by several unique, commercially available nozzle designs to Berea Sandstone, Wellington Shale, Crab Orchard, Catoosa Shale, Indiana identify flow features that might lead to improved bit and bottom hole cleaning. Limestone, Pierre Shale, Carthage Marble, among others. In some cases, Drilling simulator and field tests were conducted to correlate rate of penetration special rock cores are obtained from outcroppings of the formations of interest (ROP) improvements with identifiable flow enhancements brought about by to particular customers. Historically, a variety of oil and water based drilling nozzle design. muds have been analyzed with having mud weights as high as 16 ppg. The study concluded that small features built into the exit of a bit nozzle Erosion along the face of the bit is also a major concern in a number of have little effect on the resulting jet. The size of the exit feature is limited by the fields worldwide. To evaluate erosion rates in drill bits and other down hole small diameter of the nozzle body. The smallest features, as used by the Y, star tools, Dr. Wells has developed a particle erosion model and incorporated it and cross nozzles, tend to disappear in the flow at a distance of roughly one to

47 dynamics ISSUE 3.02 ..::FEATURE ARTICLE Oil & Gas

ABOVE Non-optimized (left) and optimized (right) cuttings transport

ABOVE A successful application of the erosion model: the overall rate of erosion on the surface of the optimised case (right) was reduced by roughly 67% compared to the original case (left)

ABOVE Polyhedral mesh of a roller cone drill bit

ABOVE ABOVE ABOVE Four of the several nozzle exit designs examined in this sudy (clockwise from upper Figure-8 nozzle Single Figure-8 nozzle directed toward the end of left): a) slot, b) Y, c) star and d) cross the blade separating two junk slots two nozzle diameters from the nozzle exit. Larger features, as seen with the were used the drill bit started balling (clogging up with drill cuttings which slot nozzle may persist for longer distances from the exit but the flow tends to dramatically reduces performance) at a rate of penetration of 52 feet per scale with the smaller dimension (width) and thus the jet decays more rapidly hour. When the Figure-8 nozzles were used, the bit did not start balling until with distance from the nozzle exit. it reached a rate of penetration of over 190 feet per hour. These results suggest that features in the nozzle exit must be relatively Balling is the situation where the reground cuttings and solid particles large to affect the structure of the jet and thereby the performance of the remaining on the hole bottom tend to adhere to the bit body, particularly in bit hydraulics. Other nozzles designs were evaluated that either force the jet sticky formations such as shales, limestones, and chalks. The configuration to swirl about its axis or redirect the jet to some angle with respect to the using a roller cone drill bit resulted in a new field record at Saudi Aramco. nozzle axis. The simulations showed the turbulent jets generated by the test nozzles differed only slightly from the standard nozzle. The laboratory drill Dr. Wells concluded: tests and field results correlated with the simulation by showing no change “These applications demonstrate that STAR-CCM+ offers the in bit performance. potential for huge advancements in drilling, especially under more Using STAR-CCM+, a new Figure-8 nozzle was designed then built to challenging conditions. STAR-CCM+ gives design engineers the address specific applications where a single bit nozzle was required to ability to easily and accurately analyze fluid flow, under harsh provide flow to two junk slots---a scenario typically referred to as split flow. realistic drilling conditions making it possible to rapidly evaluate In this environment a single nozzle is directed toward the end of the blade alternatives and provide comprehensive diagnostic information. The separating the two junk slots. A drilling simulator test was conducted to method also allows design engineers to optimize the fluid flow around evaluate the benefit of the new Figure-8 nozzle design. the drill bit during the design phase, rather than after the product has The drill tests were conducted in Catoosa Shale at 120 rpm and 290 been manufactured.” < gallons per minute (gpm) using 11/32 nozzles. When conventional nozzles i FOR MORE INFORMATION ON BAKER HUGHES PLEASE VISIT: www.bakerhughes.com

dynamics ISSUE 3.02 48 ..::FEATURE ARTICLE Marine ::::::EXTREME:::::: WEIGHT LIFTING

ABOVE Twin Marine Lifter concept

Det Norske Veritas (DNV) was founded in 1864 as a classification society. Today it ranks among the largest in the world, and it provides a wide range of services in various domains. The authors are part of the Technical Consultancy Group in DNV. www.dnv.co.uk

49 dynamics ISSUE 3.02 ..::FEATURE ARTICLE Marine

Resistance Calculation for the Twin Marine Lifter Cosmin Ciortan, Kåre Bakken, Det Norske Veritas (DNV) WEIGHT LIFTING Twin Marine Heavylift AS (TMHL) is designing the Twin Marine Lifter system for installing and removing platforms. Each of the two heavy lifters has 4 rectangular buoyancy elements at one side, helping to lift the platform (on site) and place it on the bigger transport vessel. The buoyancy tanks are a challenge when assessing both resistance and course stability. DNV was called to assess the viscous resistance in calm water, the forces on the buoyancy tanks and course stability.

Transporting the platforms from one location offshore to The prescribed ship motion was advancing head-on, with no incidence onshore for dismantling and recycling is a cheaper and more angle to the flow. The simulations were performed for velocities of 3, 5, environmentally friendly option than destroying them offshore. 7 and 10kn. For the 3 and 5kn simulations, the free surface was not Twin Marine conceived a system that achieves this using a Twin Marine considered. The ship and tanks were not allowed to sink and trim; they Lifter system (TML). The system features buoyancy tanks on one side were considered on even keel. of the ship, which help lifting the platform by taking part of the weight. The ship is 133m long and 40m wide, with a transit draught of 5.35m. Results The buoyancy tanks are rather large, with a rectangular section of 10m The presence of the tanks makes it difficult to validate the results against x 12m. In transit condition, the draught of the buoyancy tanks is 8.9m. traditional hulls predictions. It was decided to check the methodology by Obviously, the presence of large blunt bodies at the side of the ship performing a simulation of the bare hull, without the tanks and with will have a large influence on the resistance and course stability. Vortex no free surface effects. Therefore, the results refer to the viscous shedding is certain to be an issue for flow analysis. In addition, the resistance only, and as such can be compared with the ITTC ’57 formula. interaction between the buoyancy tanks and the hull is another problem Even so, as the ITTC ’57 formula refers to a flat plate, a shape to tackle. coefficient must be employed. The value of the shape coefficient was The simulations were performed using STAR-CCM+. Two grids estimated to be 0.35 for a perfect match with the results. But considering were used in order to check the sensitivity of the results to grid that a typical value for a Very-Large Crude Carriers (VLCCs) is about 0.25 coarseness, using around 4 and 5 millions cells respectively. Trimmed and that the VLCCs bodies in our case are more slender and streamlined cells were used, with prisms layers around the hull and tanks and than average, the value of 0.35 seems realistic. g increased refinement in their vicinity.

dynamics ISSUE 3.02 50 ..::FEATURE ARTICLE Marine

TML SYSTEM MAIN HINGE HINGE SUPPORT BALLAST TANKS

SKID WAGON

SKID RAILS ON DECK

TELESCOPE BEAM & LOAD POINT

QUICK EVACUATION TANKS VERTICAL HYDRAULIC CYLINDER

BUOYANCY TANKS

SKID RAILS FOR BUOYANCY TANK FRAMES BUOYANCY TANK GUIDE FRAME VERTICAL HYDRAULIC CYLINDER

ABOVE Schematic of Twin Lifter

The results showed strong vortex shedding due to the tanks and to the flow interaction between them. As a consequence, the individual and total resistance components display a highly irregular pattern in time. The jumps in the curves close to 200s are due to the change of meshes. The most interesting feature is that Tank 1 (the forwardmost one) displays the highest resistance, accounting for about 66% of the total resistance. It is also notable that Tank 2, which is located right behind Tank 1 Tank 2 Tank 3 Tank 4 Hull Total Tank 1, displays a positive value of the resistance, i.e. it is sucked forward in the wake of Tank 1. Tank 3 gets back to the expected sign of resistance, though its value is low, whereas the resistance of Tank 4 is larger. The time-averaged, stabilized values of the individual and total resistance show a rather regular increase with velocity and confirm the observation that Tank 1 contributes the most to the total resistance and that Tank 2 is sucked forward by Tank 1. The rotation moment is rather large, and increases significantly with the velocity. A quick calculation indicates that at a speed of 7kn, the ship should sail at an incidence angle of about 9 degrees. About 12% of the

installed thrust would be required to keep the ship on straight course. Tank 1 Tank 2 Tank 3 Tank 4 Hull Total A dynamic course keeping is mandatory, considering the quick and irregular oscillations of the vertical rotation moment.

Conclusions This case shows that CFD (and STAR-CCM+ in particular) can be successfully used for tackling complex phenomena, with useful results and in a reasonable period of time. The results indicate a periodic pattern of the flow around the hull tanks. The flow is dominated by vortex generation due to the presence of the tanks, and this influences the resistance value for each tank and for the ship. <

RIGHT Resistance and Rotation Curves

51 dynamics ISSUE 3.02 ..::FEATURE ARTICLE Marine

ABOVE Free surface around the hull and tanks, 10 kn

ABOVE, RIGHT & BELOW TML Illustration

ABOVE Velocity vectors on the free surface i FOR MORE INFORMATION ON DNV PLEASE VISIT: www.dnv.com

dynamics ISSUE 3.02 52 ..::FEATURE ARTICLE Marine

RANS*Simulation of Complex Marine Flow Problems

[*Reynolds-Averaged Navier-Stokes]

Claus D. Simonsen, Senior Specialist, Hydro and Aerodynamics, FORCE Technology.

Computational Fluid Dynamics (CFD) is becoming a major element in the consultancy services that FORCE Technology offers to its clients

FORCE Technology is a in the marine sector. global provider of hydro- and aerodynamic consultancy As the application of CFD to design, evaluation and The goal of this project was to build the complete CFD model services to the ship and optimization of ships and off-shore structures in of a ship, including appendages and operating propeller, in offshore industry. The services cover their early development stage increases, and more order to study the flow field, compute the hydrodynamic loads experimental wind tunnel complex geometries and operations are being considered, a and validate the results against experimental data. and towing tank testing plus thorough knowledge and a solid experience of the CFD tools-- Due to the complexity of the problem, the appended hull advanced CFD simulations. In addition to this, FORCE including validation against experiments - is required to meet and the propeller were first modeled individually. Afterwards, Technology also develops the present and future challenges related to practical flow the two models were combined by means of sliding interfaces maneuvering simulators problems. to simulate the entire configuration. All calculations were and provides training in our full mission maneuvering To test and demonstrate the capabilities of RANS-based CFD conducted in model scale. The complete simulation process, simulators. in connection with complex ship flows, FORCE Technology, from meshing through to post-processing was performed MAN Diesel A/S and DTU in Denmark have recently been entirely within the STAR-CCM+ integrated environment. involved in a project under DCMT [Danish Centre for Maritime For the simulation of the propeller alone, an open-water Technology]. configuration was considered. In this setup, the propeller is

53 dynamics ISSUE 3.02 ..::FEATURE ARTICLE Marine

ABOVE Instantaneous pressure field on the stern region of the hull and on the propeller

advancing through undisturbed water with no hull in front of it. The propeller At the typical operation point of the propeller, both thrust and torque were settings, i.e. advance speed and RPM, were taken from an experimental predicted within 3.4% of the measured values. open-water test to allow direct comparison between CFD and measurement. For the hull alone, the flow was calculated in a traditional resistance A polyhedral mesh was used. The flow solver was run in steady mode with test setup. Dynamic sinkage and trim were not predicted, so the model was the rotation of the propeller modeled using the moving reference frame positioned according to the measured dynamic sinkage and trim position. approach. The speed was taken equal to 1.915 m/s, which corresponds to a Froude One of the principle advantages of CFD simulation regards the ability and Reynolds numbers of Fr = 0.289 and Re = 7.24 millions respectively. to visualize the flow, which gives the engineer a valuable insight into the Trimmed cells were used for the mesh. The effect of the free surface was performance of the design, not easily available using alternative means. included via the two-phase VOF model available in STAR-CCM+. For instance, it provides information about the hydrodynamic loads on the Comparison between computed and measured data shows that the propeller, i.e. the propeller thrust and torque. Comparison between calculated resistance was calculated within 2.4% of the measured value. open-water data and data measured in FORCE Technology’s towing tank To check the grid quality, a grid study on three different grids was made; it shows that the computed data agrees fairly well with the measurement. showed that the calculated resistance changed by 11% between coarse g

dynamics ISSUE 3.02 54 ..::FEATURE ARTICLE Marine

and medium grids, while it changed by 1% between medium and fine grids. The fine grid was used for the comparison above. The nominal wake field behind the ship at the propeller plane is important for the design of the propeller and is therefore often extracted from CFD simulations. In this case, the ship is relatively slender, so the bilge vortices - which are normally observed in the centre plane wake - are relatively weak. Consequently, the wake contours are smooth. After calculating the hull and propeller flows individually, the components were combined in order to perform a simulation at the self-propulsion condition. The propeller RPM corresponding to self-propulsion were taken from a previous model test conducted by FORCE Technology. The ship speed was set at 16 knots, corresponding to a Froude number of 0.34. Since the propeller was operating in a non-uniform flow field behind the ship, the simulation was run in transient mode, i.e. time accurate. The propeller was physically rotated by means of a rigid body motion and sliding interfaces. Again, the free surface was modeled using the VOF model. The resistance and propeller quantities were predicted within the same ABOVE accuracy of the measurement as found in the individual models. A study of Nominal wake field behind the ship at the propeller plane and axial velocity contours the field quantities, i.e. velocity and pressure in the stern region, showed a time varying but periodic flow field while a study of the flow field over time showed that the load on the propeller blades varies with the blade position due to the non-uniform propeller inflow field behind the ship. Furthermore, pressure pulses on the hull above the propeller were observed when the blades passed the twelve o’clock position. The post-processing results also illustrates how the propeller accelerates the flow and introduces swirl over the rudder downstream of the propeller. The propeller blade tip vortices could also be traced over the rudder. Consequently, the model provides information which may be useful for rudder design.

Conclusion The present study shows an example on how STAR-CCM+ can be applied to solve practical flow problems in the marine industry. Flow visualization gives a valuable insight into the physics of the flow problems. Further comparisons between calculated and measured hydrodynamic forces and moments show that STAR-CCM+ results agree fairly well with measured data, which increases the level of confidence in STAR-CCM+ for its application to the evaluation of design variants in the early development stage. < ABOVE Tangential velocity field in stern region

BELOW Breaking bow wave

i FOR MORE INFORMATION PLEASE VISIT: www.force.dk

55 dynamics ISSUE 3.02 ..::FEATURE ARTICLE Marine

RIGHT Pressure distribution on propeller suction side

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