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A N S Y S Advantage Volumen 1 Issue 1 2007


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ANSYS Advantage Magazine Volumen 1 Issue 2007

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A N S Y S Advantage Volumen 1 Issue 1 2007

  2. 2. EDITORS’ NOTEWelcome to ANSYS Advantage! With the strategic acquisition of used in their development efforts, for example. Likewise, Fluent Inc. and blending of their CFD analysts can better understand the tools used to gain leading-edge CFD technologies with insight into the mechanical behavior of products. its existing core software offerings, Our editorial team is proud to present this premier ANSYS, Inc. has further strengthened issue. The feature articles highlight applications in which its position in having one of the multiple simulation technologies are used. For example, broadest, most comprehensive, inde- our cover story discusses how Hawkes Ocean Technologies pendent engineering simulation used ANSYS CFX software to minimize drag in the design software offerings in the industry. of an innovative two-man oceanographic craft and ANSYS The combined user base is vast, Mechanical tools to ensure that composite parts withstand comprising one of the world’s largest underwater pressure without being overdesigned with simulation communities with com- excess material. At the center of the magazine, a 16-page mercial seats at more than 10,000 supplement shines a spotlight on applications in the sports companies, including 94 of the top and leisure industry that range from the design of alpine FORTUNE 100 industrial companies. skis to fitness equipment. One of the best ways to serve this We invite you to consider ANSYS Advantage your growing simulation community is with magazine, not only providing information about software a single publication providing a forum products and technology applications but also giving you afor the exchange of ideas, a conduit for technology transfer way to share your work with colleagues in the simulationbetween disciplines and a common framework for inte- community. We welcome your feedback and ideas forgrating so many diverse areas of interest. With this in mind, articles you might want to contribute. Most importantly, wethe former Fluent News and ANSYS Solutions publications hope you find the publication to be a valuable asset inhave been merged into the new quarterly ANSYS Advan- implementing simulation-based product development intage magazine covering the entire range of ANSYS your own workplace. Itechnologies and applications. One of the greatest benefits of a single magazine is theopportunity for readers to become familiar with software andapplications beyond their usual fields of interest. Mechanicalengineers accustomed to using ANSYS primarily forstructural analysis may see how the use of CFD could be Liz Marshall and John Krouse, EditorsFor ANSYS, Inc. sales information, call 1.866.267.9724, or visit subscribe to ANSYS Advantage, go to Contributing Editors Editorial Advisor About the Cover: About the sportsLiz Marshall Erik Ferguson Kelly Wall Contours of pressure supplement: Keith Hanna on the surface of an The flow field in theConsulting Editor Fran Hensler Circulation ManagerJohn Krouse Marty Mundy Elaine Travers underwater craft vicinity of a golf ball Chris Reeves developed by Hawkes immediately afterAssistant Editor/ Designers Ocean Technologies being struck by a clubArt Director Ad Sales Manager Miller Creative GroupSusan Wheeler Beth MazurakEmail: ansys-advantage@ansys.comANSYS Advantage is published for ANSYS, Inc. customers, partners and others interested in the field of design and analysis applications.Neither ANSYS, Inc. nor the editorial director nor Miller Creative Group guarantees or warrants accuracy or completeness of the material contained in this publication.ANSYS, ANSYS Workbench, CFX, AUTODYN, FLUENT, DesignModeler, ANSYS Mechanical, DesignSpace, ANSYS Structural, TGrid, GAMBIT and any and all ANSYS, Inc.brand, product, service, and feature names, logos and slogans are registered trademarks or trademarks of ANSYS, Inc. or its subisdiaries located in the United Statesor other countries. ICEM CFD is a trademark licensed by ANSYS, Inc. All other brand, product, service and feature names or trademarks are the property of theirrespective owners.© 2007 ANSYS, Inc. All rights reserved.
  3. 3. TABLE OF CONTENTS Contents FEATURES Multi-Tool Analysis 3 3 Taking Next-Generation Submersibles to New Depths ANSYS simulation tools help minimize drag and reduce weight by half in two-man oceanographic craft. 6 Fluid Structure Interaction Makes for Cool Gas Turbine Blades An integrated simulation process improves performance without sacrificing longevity. 9 Race Cars Flex Their Muscle An Indy car rear wing is designed for aeroelastic response using 6 multidisciplinary optimization. 12 Modern Medicine Takes Simulation to Heart A fluid structure interaction simulation is performed to capture patient-specific modeling of hypertensive hemodynamics. Applications 14 CONSUMER PRODUCTS CAE Takes a Front Seat Engineers use ANSYS software to meet complex and potentially conflicting 9 requirements to design a chair for a wide range of body types and postures. 16 PHARMACEUTICALS Transport of Fragile Granules Pneumatic conveying systems in the pharmaceutical industry can lead 12 to unwanted particle breakup. 18 CHEMICAL PROCESSING Solid Suspensions Get a Lift 14 A high-efficiency hydrofoil is designed using CFD and multi-objective optimization software. 20 GLASS The Many Colors of Glass Numerical simulation helps guide the color change process in the glass industry. 22 POWER GENERATION Developing Power Systems that Can Take the Heat18 Integrating ANSYS technology with other software enabled researchers to efficiently assess component reliability for ceramic microturbine rotors. 25 AUTOMOTIVE 20 No Shivers While Developing the Shiver Tools within the ANSYS Workbench Environment have allowed engineers to get a handle on crankshaft behavior before a motorcycle is built. 22 26 Putting the Spin on Air Pre-Cleaners Dust and dirt particles are removed from the air intakes of off-highway vehicles using a novel air pre-cleaner. (Continued on next page) ANSYS Advantage • Volume I, Issue 1, 2007 1
  4. 4. TABLE OF CONTENTS 29 METALLURGY Blast Furnace Air Pre-Heater Gets a Thermal Boost Engineers use CFD to improve heat exchanger performance. 30 Fire Tests for Molten Metal Converters Numerical simulation helps engineers peer into a metallurgical converter in which high temperatures and adverse conditions make realistic measurements impossible to perform. 32 EQUIPMENT MANUFACTURING Neutrino Detection in Antarctica Simulation helps speed up drilling through ice so that optic monitors can be installed. Spotlight on Engineering Simulation in the 34 MATERIALS Sports and Leisure Industry Making Sure Wood Gets Heat Treated s2 Sporting Swifter, Higher and with Respect The ANSYS Parametric Design Language helps establish the Stronger Performances with thermal conductivity of wood and composites to enable more Engineering Simulation effective heat treatment processes. Computer-aided engineering plays a major role in the world of sports.Departments s4 Catching the Simulation Wave Surfers are using engineering simulation to improve their gear. 36 THOUGHT LEADERS Accelerated Product Development s6 Giving Ski Racers an Edge in a Global Enterprise ANSYS Mechanical software is used to analyze the dynamic With the goal of compressing cycle times by up to 50 percent, the Velocity properties of skis. Product Development (VPD™) initiative at Honeywell Aerospace uses engineering simulation to eliminate delays while lowering cost and s8 Ice Axe Impacts maintaining high quality standards for innovative designs. Finite element analysis is used to study crack initiation on a serrated blade. 38 ACADEMIC NEWS Stent Analysis Expand Students’ Exposure s9 Tour de Force! to Biomedical Engineering Aerodynamic gains can be realized by studying the Engineering students gain insight into the physics of medical devices and interaction between a bicycle and rider. add to the body of knowledge on stenting procedures. s10 Speeding Up Development Time 40 Designing a Course for Future Designers for Racing Cycles Students use Volvo concept car to learn about simulation tools. Trek Bicycle Corporation cuts product launch delays with simulation-based design using ANSYS Mechanical software. 42 ANALYSIS TOOLS Introducing the PCG Lanczos Eigensolver s11 Scoring an HVAC Goal for A new eigensolver in ANSYS 11.0 determines natural frequencies Hockey Spectators and mode shapes using less computational power, often in CFD is used to design ventilation systems for sports arenas. shorter total elapsed times than other tools on the market. s13 Taking a Bite out of Sports Injuries 44 TIPS & TRICKS Finite element analysis illustrates that both cushioning and CAE Cross Training support are needed to adequately protect teeth and Engineers today need to be proficient in not one, but many analysis tools. surrounding tissue from impact injuries. 46 View-Factoring Radiation into ANSYS s14 Designing Fitness Equipment to Workbench Simulation Withstand the Workout The ANSYS Radiosity Solution Method accounts for heat exchange between Keeping bushing wear rates under control allows Life Fitness surfaces using Named Selections and a Command object. to maintain some of the highest equipment reliability standards in the fitness industry. 48 PARTNERSHIPS Going to the Source s16 Catching a Better Oar Design MatWeb material property data is seamlessly available to Engineers use CFD and a spreadsheet model to assess ANSYS Workbench users. prospective oar blade designs.2 ANSYS Advantage • Volume I, Issue 1, 2007
  5. 5. MULTI-TOOL ANALYSIS Winged-submersibles designed by Hawkes Ocean Technologies “fly” through water to depths of 1,500 feet using controls, wings and thrusters similar to jet aircraft. To identify critical forces such as drag, weight, pressure and stresses as well as optimize design, the engineering team used ANSYS simulation software including ANSYS CFX and ANSYS Mechanical. Access to simulation applications and Hawkes’ chosen CAD through a single, integrated platform — ANSYS Workbench — helped streamline the development process.Taking Next-GenerationSubmersibles to New Depths By Adam WrightANSYS simulation tools help minimize drag and reduce Hawkes Ocean Technologiesweight by half in two-man oceanographic craft. California, U.S.A. The world beneath the ocean surface is teeming withmost of earth’s animal and plant species. While three-quarters of our planet lies under water, less than 5 percenthas been explored, mainly because of shortcomings intoday’s research equipment. Scuba limits divers to thetopmost slice of the oceans. Conventional submersibles, onthe other hand, are designed to drop like bricks into theocean depths using variable buoyancy to control dive depthwith bulky air tanks, compressors, pumps and piping. As aresult, they have limited maneuverability and need adedicated mother ship to transport and maintain them.Furthermore, the loud operational noise and brightlights associated with these crafts scare away manysea organisms. Hawkes Ocean Technologies has come up with asolution to move beyond these constraints: a new class ofsmall, highly maneuverable craft that can be piloted throughthe water to a desired depth using controls, wings and ANSYS CFX computational fluid dynamics software helped develop the overallthrusters for undersea flight similar to that of a jet aircraft. streamlined shape of the external fairing to minimize underwater ANSYS Advantage • Volume I, Issue 1, 2007 3
  6. 6. MULTI-TOOL ANALYSISANSYS Mechanical software was used extensively for stress analysis in ensuring that The Wet Flight is a high performance one-person sub designed for underwater filming.the pressurized pilot compartment hull could safely withstand 700 psi at quarter-miledepths without overdesigning components with excess material.In this way, the company’s winged-submersible concept pressures of nearly 700 psi. In particular, the compartmentcombines the vision and low-intrusiveness of scuba diving hull protecting pilots from this crushing pressure is awith the depth capability of a conventional submersible. cocoon-like contoured structure designed to maximize An internationally renowned ocean engineer and space in order to maintain comfort: a significant designexplorer, company founder Graham Hawkes holds the world factor because an occupant tends to become cramped andrecord for deepest solo dive of 3,000 feet and has been possibly claustrophobic after an hour or two beneath theresponsible for the design of hundreds of remotely operated great mass of water above. Another complicating factor inunderwater vehicles and manned underwater craft built for determining component stress distribution was theresearch and industry worldwide. The Deep Rover sub- anisotropic nature of the composite material properties,mersible, for example, is featured in James Cameron’s 3-D which have different strengths in each direction dependingIMAX film “Aliens of the Deep,” and the Mantis craft on the orientation of the carbon fiber.appeared in the James Bond film “For Your Eyes Only.” In addition to ensuring adequate strength of the craft, Based near San Francisco Bay, California, U.S.A., designers had to optimize tradeoffs between powerHawkes Ocean Technologies is an award-winning design and weight. One problem to be addressed was that ofand engineering firm with a small staff of dedicated profes- minimizing the underwater drag of the external fairing tosionals who use ANSYS software to help them develop achieve maximum speed with minimal power consumption.their innovative craft. Hawkes’ winged submersibles, which The right balance allows the craft to sustain the speedare based on the concept of underwater flight, are rated for needed by the airfoils to overcome positive buoyancy whilea depth of 3,000 feet; the next-generation submersibles extending the range. Since the winged craft must keepalready have been tested down to 20,000 feet. The model moving at about two knots to remain submerged, this was acurrently being designed and built is a next-generation two- critical craft with lightweight carbon-reinforced compositematerial replacing the aluminium parts of the previous The Solutionmodel. A pressurized pilot compartment hull and electronic To address these design issues, Hawkes engineersequipment housings are made of a filament-wound turned to simulation tools within the ANSYS Workbenchcomposite, while the streamlined exterior skin of the craft is environment. To minimize drag, ANSYS CFX computationalmade of layered fabric composite. Transparent acrylic fluid dynamics software was used to develop the overalldomes provide 360-degree visibility and minimize distortion streamlined shape of the external fairing. The analysisdue to water boundary refraction. defined the flow around the fairing and enabled researchers to readily pinpoint any areas of excessive turbulence. TheChallenges of Withstanding Pressure results helped them configure the shape for minimum One of the most difficult aspects of designing the new hydrodynamic resistance and maximum lift and effective-craft involved the determination of stresses in the complex ness of the airfoil surfaces for allowing the craft to dive andgeometries of the composite parts that must withstand maneuver underwater.4 ANSYS Advantage • Volume I, Issue 1, 2007
  7. 7. MULTI-TOOL ANALYSISThe Deep Flight II can house one or two persons in a prone position The Wet Flight submersible rises to the surface.and can travel for up to eight hours. When diving to 1,500 feet and deeper depths, there is an analysis and quickly perform another simulation on theno room for error, so Hawkes used ANSYS Mechanical new part geometry without having to re-apply loads,software for stress analysis to ensure that composite supports and boundary conditions. For some cases, moreparts could withstand underwater pressure without being than 40 design iterations were tested. The approach savedoverdesigned with excess material. The program readily considerable time and effort, allowed numerous alternativeaccounted for the anisotropic material properties of the configurations to be studied, guided engineers toward thecomposite parts and clearly showed directional stresses uniquely contoured compartment hull shape, and, perhapsgraphically as well as numerically with precise von Misses most importantly, minimized mistakes. In this way, thevalues. The capability helped engineers determine the researchers were able to quickly arrive at a not-intuitively-proper carbon fiber orientation and wall thickness needed obvious optimal design for a craft that could withstandto strengthen high-stress areas of composite parts, particu- prescribed pressure limits with minimal weight and fit withinlarly the pressurized pilot hull. the tight space constraints of the two-man submersible. The stress levels of assemblies of individual parts madeof different materials also were analyzed. For example, one Significant Weight Reductionassembly included the metal locking ring that clamps the By using ANSYS software in the design of componentsfittings and seal of the acrylic dome to the composite hull, to be made with composites instead of aluminium,along with the dome and hull. In generating these assembly engineers were able to reduce the overall weight of the craftmodels, the ANSYS surface-to-surface contact element by 50 percent. This significant weight reduction is expectedfeature automatically detected the contact points, allowed to increase maximum underwater speed and save batteryfor different material properties and adjusted mesh life to increase the time the craft can spend underwater.densities instead of requiring users to perform these tasks Because the lightweight submersible does not need amanually. Moreover, convenient element-sizing functions dedicated mother ship, operational costs are reduced byenabled engineers to readily increase mesh density in 70 percent and the craft can operate freely worldwide off oflocalized regions in which they wanted to study stresses in a variety of launch platforms. This greatly expands thegreater detail. underwater exploration possibilities of the craft. Further- Easy access to computer-aided design (CAD) software more, these next-generation submersibles hold theand simulation applications through the integrated ANSYS potential of unlocking new biotechnology from the oceanWorkbench platform allowed Hawkes engineers to become depths that may help cure disease, discovering newproductive on the first day. Simulation models were created aquatic species, finding new mineral and food reserves,based on part geometry from the Autodesk® Inventor TM studying weather, and providing a means to monitor anddesign system. Direct associativity with the CAD system prevent further pollution at sea. Ienabled engineers to readily change the design based ANSYS Advantage • Volume I, Issue 1, 2007 5
  8. 8. MULTI-TOOL ANALYSISFluid Structure Interaction Makesfor Cool Gas Turbine BladesAn integrated simulation process improves performancewithout sacrificing longevity.By Michel Arnal, Christian Precht and Thomas Sprunk, Wood Group Heavy Industrial Turbines AG, SwitzerlandTobias Danninger and John Stokes, ANSYS, Inc. In gas turbines, hot gas from the combustion system flows past the rotating turbine blades, expanding in the process. In order to reach desired levels of efficiency and power output, advanced gas turbines operate at very high temperatures. As a result, the components subjected to these high temperatures often require cooling. One method of cooling the turbine blades involves extracting air from a compressor and forcing it through a plenum and into channels inside the blade. While effective cooling of the blades can increase their lifespan, it can also reduce the thermal efficiency of the engine. It is therefore important to develop designs that extend com- ponent life while having a minimal effect on engine thermal efficiency. Numerical simulations that accurately capture the interaction between the fluid and thermal effects can play an important role in the design process. Wood Group Heavy Industrial Turbines provides a comprehensive range of support solutions, including re-engineered replacement parts and maintenance, repair and overhaul services for industrial gas turbines andThe blade geometry related high-speed rotating equipment used in the global power generation and oil and gas markets. One example of the work done by Wood Group is a recent project involving the re-engineering of the blade from the The internal features of the blade geometry include the first stage of a gas turbine. The goal of plenum (blue) and the cooling channels (gold). the project was to optimize the blade design and improve its longevity. The numerical simulation process coupled ANSYS CFX software for the fluid flow, ANSYS Mechanical software for the6 ANSYS Advantage • Volume I, Issue 1, 2007
  9. 9. MULTI-TOOL ANALYSISstructural response of the blade, and the1-D thermal and fluid flow simulationpackage Flowmaster2. This set ofsimulation tools provided an efficient Hotvirtual prototype that was used to Gasassess the performance of the turbineblade under actual operating conditions. 1-D ChannelCFD Model (Flowmaster) The original 3-D CAD geometry,which is intended for manufacturing, Bladewas extended for the purpose of thesimulation using ANSYS DesignModeler.The extensions served to better representthe true operating conditions of the rotor. 3-D CFD (ANSYS CFX)For example, gaps not present undernormal operating conditions were closed. PlenumThis extended CAD model then served asthe basis for the CFD mesh. The two fluid domains (the hot gasflow around the blade and the coolant 3-D FEAairflow in the plenum) and one solid (ANSYS Mechanical)domain (the blade itself) were meshedindependently using ANSYS ICEM Overview of the interaction between the simulation A schematic of the two fluid (blue and red) and one tools used to provide a virtual prototype of the gas solid (gray) domain used to perform the analysis.CFD meshing software. Generalized turbine blade. Boundary conditions are defined at locations indicatedgrid interfaces (GGIs) were used to with arrows. The green lines indicate generalized grid interface connections. The inflow to the hot gasconnect the non-matching mesh domain from the cooling channels is described bytopologies of the individual domains. CFX Expression Language callbacks to 1) the flow outThe cooling channels were modeled of the plenum domain and 2) the heat transfer from the solid domain to the cooling channels.using Flowmaster2, and the result ofthis 1-D simulation was connected toANSYS CFX using the standard CFXExpression Language (CEL), whichrequires no user programming. Takingadvantage of CEL callback functions,the coolant air flow in the plenum, thehot gas around the blade and the heatconduction through the solid blade canbe solved for in a single ANSYS CFXsimulation. At the same time, the CFDsimulation can use the unique ANSYSCFX model for laminar to turbulenttransition, a key feature that properlycaptures heat transfer rates from thehot gas to the blade surface as theboundary layer develops. The tempera-ture field in the solid blade ascomputed by ANSYS CFX softwarewas then directly written out in a formatappropriate for the subsequent ANSYSMechanical calculation.FE Model For the simulation using ANSYS ANSYS ICEM CFD mesh of the hot gas fluid domain at the tip of the gas turbine bladeMechanical software, the 3-D tempera-ture field in the solid blade, calculated ANSYS Advantage • Volume I, Issue 1, 2007 7
  10. 10. MULTI-TOOL ANALYSISthe ANSYS CFX conjugate heat transfer structural analysis with a 1-D thermalanalysis, was used as input for the simulation, this virtual prototype hasthermal load. This, along with the rota- provided a more complete under-tional load on the blade at operating standing of the performance of eachconditions, determined the stress blade design in a given set ofdistribution. Together, the resulting operating conditions. This allows mod-thermal and mechanical stress distri- ifications to be made early in the The finite element meshbutions in the blade were used to design process, and therefore isdetermine component life. Applying essential in the efforts to help improvethese loads, life-limiting elements of efficiency and increase longevity. Ithe blade design could be determinedand new design alternatives evaluated. Suggested Reading The ability to combine the entire Arnal, Michel; Precht, Christian; Sprunk, Thomas;fluid and thermal analysis through the Danninger, Tobias; and Stokes, John: Analysis ofuse of standard functionality, especially a Virtual Prototype First-Stage Rotor Blade Using Integrated Computer-Based Design Tools. Pro- a)the powerful CFX Expression Language ceedings of ESDA2006 8th Biennial ASMEand its callback functions, are key Conference on Engineering Systems Designto making simulations such as this and Analysis, Torino, Italy, July 2006.feasible. By combining both CFD and b) c) Stress distribution in the directionally solidified blade ANSYS CFX temperature simulation of the CFD simulation of heat flux distribution. The due to a) temperature variations (but not including blade surface. Streamlines show flow from heat transfer is from the hot gas to the blade rotational effects), b) centripetal forces (assuming a the inlet into the plenum and from the cooling surface in most areas, but in the tip region constant temperature) and c) the combination of channel outlets into the hot gas. Where the the heat transfer is positive corresponding to temperature variations and centripetal forces internal cooling channels are close to the where the cooling air from the cooling holes blade surface on the suction side of the blade comes into contact with the blade surface. near the trailing edge, areas of lower temper- ature are shown in blue. Temperature contours in the flow field and through the blade at a radial location near the blade platform (left) and outer casing (right)8 ANSYS Advantage • Volume I, Issue 1, 2007
  11. 11. MULTI-TOOL ANALYSISRace Cars Flex Their MuscleAn Indy car rear wing is designed for aeroelastic response usingmultidisciplinary optimization.By David Massegur, Giuseppe Quaranta andLuca Cavagna, Department of Aerospace EngineeringPolitecnico di Milano, Italy Aerodynamics play a crucial role in the perform- ance of race cars, such as Indy and Formula 1, and for years, teams have spent a great deal of time and money on wind-tunnel testing. Nowadays, thanks to increases in computational power, CFD has become a valuable tool for fine-tuning both the external and internal shape of these cars. The goal is to maximize downforce, in order to increase cornering speeds, and to reduce drag to be faster on the straights. Thus, the highest aerodynamic efficiency is sought that represents the optimal trade-off between high downforce at low speeds (for cornering) and low drag at high speeds (for driving on the straights) [1]. To improve car performance at the different operating conditions, the flexibility of aerodynamicPathlines illustrate the presence of the flow recirculation behind the gurney flap. devices (aeroelastic effects) can be exploited. In fact, the changes in the shape of such devices due to deformation may cause a modification of the flow field around the car. Despite being severely restricted by technical regulations, this currently is the only way to optimize the car for different ANSYS Advantage • Volume I, Issue 1, 2007 9
  12. 12. MULTI-TOOL ANALYSIS of the track because any servo-aided device aimed at moving an element of the car is strictly forbidden. Since aerodynamic loads increase quadratically with speed, aero- elastic phenomena can be exploited more easily at high speed, where the pressure loads cause larger deformations. A multidisciplinary computational model has been1. Main wing developed at the Politecnico di Milano to evaluate, by2. Flap wing means of numerical optimization, possible geometric and3. Gurney flap4. End-plates structural configurations of race car rear wings in order to5. Supports tailor aeroelastic phenomena to maximize car performance. The model has been applied to the DALLARA Indy car rear wing. The focus of the study has been on the influence of the structural deformation of the carbon-fiber flap on the aerodynamic loads of the whole rear wing assembly. Future applications will investigate the effects of other deformable parts, such as the pillar junctions. The multidisciplinary optimization requires the develop- ment of a static aeroelastic algorithm to compute the correct loads. In this case, CFD is the perfect tool for predicting the complex flow phenomena around the wings, such as the flap influence on the main wing and the twin- vortex recirculation around the gurney flap [1]. FLUENT has been used for the CFD calculation, because it is able to run steady-state, Reynolds-averaged Navier-Stokes (RANS) models with relatively modest computational resources. The aeroelastic problem is solved by applying an itera- tive procedure based on a sequence of load calculations by means of CFD for a given shape followed by an FEM calcu-The main elements that form the rear wing (top) and their lation to compute the deformation based on the CFD loads.respective discretization (bottom) The software NASTRAN® is used for the structural calcula- tion, and the sequence is run until convergence is reached. The adoption of two different solvers for the fluid and struc- ture provides the freedom to choose the optimal discretization method for each, but it requires the imple- mentation of an interface scheme to transfer the necessary Compute aerodynamic loads information between the two calculations [2]. To transfer the of the rigid body structural displacements from the FEM model to the Compute aerodynamic surfaces of the CFD grid and the aerodynamic loads to the loads of the deformed body structural nodes, an algorithm based on the weighed moving Yes least squares (WMLS) method has been developed [3]. Transfer aerodynamic loadsNo The aeroelastic solution is managed in FLUENT soft- Check FLUENT convergence to structural nodes ware through a number of user-defined functions (UDFs) Compute structural nodes that execute the different tasks required by the iterative Let FLUENT iterate solver. Of all the tasks, the most expensive one, requiring displacement with the FEM solver almost half of the solution time, is the deformation of the Move aerodynamic grid CFD grid, used to adapt to the new wing shape after each Check structural Yes iteration. The spring-based method in FLUENT software is convergence STOP used for remeshing. It is based on the analogy between the Compute aerodynamic No computational grid and a network of linear elastic springs, gridwall vertices displacement with stiffness inversely proportional to the distance between the respective adjacent nodes. However, the deformationThe iterative method used to solve the static aeroelastic problem required by each time step typically is greater than the dimensions of the cells close to the walls, giving rise to the10 ANSYS Advantage • Volume I, Issue 1, 2007
  13. 13. MULTI-TOOL ANALYSISPressure coefficient distribution comparison between the rigid (left) and deformed (right) wingsappearance of negative cell sizes. To improve the robust- Barcelona. This initial application has shown the high gainsness of the method, an algorithm has been implemented to that can be potentially achieved by multidisciplinaryadaptively subdivide the required deformation into sub- optimization for race cars. Significant improvements aresteps with achievable deformations. expected by applying the proposed method to other aero- The net result of the approach has been a multi- dynamic surfaces, such as the front wing and the diffusers. Iobjective optimization of both the wing geometry andstructural characteristics to increase downforce at low Acknowledgmentspeeds and decrease drag at high speeds. The response The authors wish to acknowledge the help of Ing. Toso of DALLARA for supporting this research.surface method (RSM), driven by the Design of Experiments(DOE) technique [4], has been used to run the cases. This Referencesapproach limits the total number of required analysis yetallows up to 20 design variables, such as the composite [1] J. Katz: Aerodynamics of Race Cars, Annual Review of Fluid Mechanics, University of California, U.S.A. (2006).material properties, number and orientation of the plies indifferent zones of the wing, the wing angle of attack, the [2] L. Cavagna, G. Quaranta, P. Mantegazza, E. Merlo, D. Marchetti, M. Martegani: Flexible Flyers in the Transonic Regime, Fluent News,wing sweep and spanwise twist. The optimization [5] is Spring 2006.subject to design constraints relative to the fulfillment of [3] G. Quaranta, P. Masarati, P. Mantegazza: A Conservative Mesh-Freeflexibility tests required by regulations and material strength. Approach for Fluid-Structure Interface Problems, International The results from the calculations show that variations of Conference for Coupled Problems in Science and Engineering,25 percent on both downforce and drag can be obtained, Greece (2005).depending on the aerodynamic configuration. Keeping the [4] D. C. Montgomery: Design and Analysis of Experiments, Wileysame level of downforce delivered while cornering, wing International Edition, New York, U.S.A. (2001).drag can be reduced by 3 percent. As a result, the car top [5] I. Das, J. Dennis: Normal-Boundary Intersection: An Alternate Methodspeed can be improved by 1 km/hr, which represents a gain for Generating {Pareto} Optimal Points in Multicriteria Optimizationof half a tenth of a second per lap in tracks such as Problems},SIAM Journal on Optimization, 8 (1998).Two examples of a swept wing, introduced as a variable of the multi-objective optimization, are a back-swept (left) and a front-swept (right) ANSYS Advantage • Volume I, Issue 1, 2007 11
  14. 14. MULTI-TOOL ANALYSISModern Medicine TakesSimulation to HeartA fluid structure interaction simulation is performed to capturepatient-specific modeling of hypertensive hemodynamics.By Kendall S. Hunter, Department of Pediatrics, Section of Cardiology, University of Colorado Health Sciences Center, Colorado, U.S.A. Could simulation technology more commonly associated with rocket science and magnetic resonance imagingand race cars someday provide insight into the inner workings of the vascular (MRI). While these methods aresystem that would help doctors provide improved diagnosis treatment in clinical effective in the diagnosis of vascularsituations? Researchers at the University of Colorado Health Sciences Center pathologies, they cannot currently(UCHSC) have taken the first steps toward that end, and the ANSYS fluid struc- provide enough detail or be performedture interaction (FSI) solution is proving to be a key enabling technology. with sufficient frequency to elucidate The pulmonary arteries are the blood vessels that carry oxygen-poor blood the causes of disease progression andfrom the right ventricle of the heart to the small arteries in the lungs. For a healthy are hard pressed to predict the out-individual, the normal average pressure in the pulmonary artery is about 14 mm come of clinical interventions. To date,Hg. For individuals with pulmonary arterial hypertension (PAH), the average pres- clinicians have mainly characterizedsure is usually greater than 25 mm Hg. This increases the load on the right side of PAH by evaluating pulmonary vascularthe heart and can lead to eventual heart failure and death. resistance (PVR), defined as the mean Diagnosis and evaluation of PAH typically is accomplished with a combina- pressure drop divided by the meantion of cardiac catheterization (in which a plastic tube is passed through the iliac flow rate. In considering only meanvein in the leg and weaved up the body, through the right side of the heart, and conditions, the effects of vascular stiff-out into the main pulmonary artery) and imaging techniques such as angiography ness are ignored; in patients with PAH, however, these effects can amount to 40 percent of the total right heart after- load. Over time, the vasculature can thicken in response to the increased pressure. Such proximal thickening and stiffening is believed to change distal flow and further increase pres- sures; thus, it may be part of a feedback loop by which PAH worsens. At UCHSC, researchers are investi- gating the impact of proximal artery stiffness by using ANSYS software to simulate the transient fluid struc- ture interaction of the blood flow and vascular walls of the pulmonary artery. By using numerical simulation, researchers can gain a better funda- mental understanding of the physics involved in PAH and insight into the effects of vascular stiffness on proxi-Mesh generated using ANSYS ICEM CFD Hexa; the CFD domain is bounded by the blue cells and the shell mesh, mal, and, perhaps more importantly,used for the structural calculation, is shown in lavender. distal hemodynamics. Eventually, the regular clinical use of patient-specific12 ANSYS Advantage • Volume I, Issue 1, 2007
  15. 15. MULTI-TOOL ANALYSISContours of pressure on the vessel walls at peak systole Contours of vessel wall displacement at peak systolesimulation, in which the vascular tage, since it allows investigations in varying mass flow boundary conditiongeometry is extracted from medical which the vessel wall thickness is at the fluid inlet with a half-sinusoidimaging, could provide better insight varied without the need for geometry profile. Exit boundary conditions wereinto the progression of PAH and modifications or re-meshing. A script modeled using CEL and a resistiveimprove predictions of the outcome of is used to apply variable shell thick- relationship in which the outlet pres-surgical intervention. ness on a node-by-node basis to the sure for each branch was determined For the ANSYS FSI simulations vessel mesh. by multiplying the local instantaneousreported here, geometry acquisition For these studies the Arruda– flow rate by a resistance factor. [1,2]begins with bi-plane angiography of Boyce hyperelastic material model is The early results of this pilotthe proximal pulmonary tree performed used. The model parameters were study have confirmed the anticipatedduring cardiac catheterization of an 18 suggested by biomechanical studies behavior of the system. Upcomingmonth-old male patient. This provides of the stress–strain properties of studies with improved clinical anddata describing the vessel centerline normotensive and hypertensive imaging data will allow validationand diameter. A CAD system is used to pulmonary arteries from a rat model and refinement of the simulationturn this skeletal data into a smooth and solid-only simulations of human methodology. Eventually, the clinicalrepresentation of the vessel geometry. pulmonary arteries. Residual stress use of non-invasive, patient-specificThe geometry is imported into ANSYS is not considered here due to the simulation may provide better under-ICEM CFD software and the Hexa difficulty of incorporating such effects standing of the progression of PAH andmeshing module is used to construct a in clinical models in which direct meas- improved predictions of the potentialhigh-quality hexahedral volume mesh. urements within the artery cannot outcomes of available treatments. IThe resulting mesh uses an O-grid be obtained. The solid model wasinflation layer from all walls so that the constrained on the inflow/outflow Referencesmesh is nearly orthogonal with excellent boundaries. The remaining nodes were [1] Vignon-Clementel, I.E.; Figueroa, C.A.;control over near-wall spacing. This allowed to deform in response to Jansen, K.E.; Taylor, C.A.: Outflow Boundarymesh is used for the CFD component applied forces. Conditions for Three-Dimensional Finite Element Modeling of Blood Flow andof the FSI simulation, solved using Blood is modeled as an incom- Pressure in Arteries. Comp. Meth. App. Mech.ANSYS CFX software. The quad surface pressible Newtonian fluid with constant Engr. (CMAME) 2006; in press.elements from that same mesh are dynamic viscosity and the flow is [2] Olufsen, M.S.: Structured Tree Outflowimported into ANSYS as a shell element assumed to be laminar. Using the CFX Conditions for Blood Flow in Larger Systemicrepresentation of the vessel. This type Expression Language (CEL), it was Arteries. Am. J. Physiol. (AJP) 276(1):of representation is a significant advan- straightforward to implement a time- H257-H268, ANSYS Advantage • Volume I, Issue 1, 2007 13
  16. 16. CONSUMER PRODUCTSCAE Takes a Front SeatEngineers use ANSYS software to meet complex and potentiallyconflicting requirements to design a chair for a wide range ofbody types and postures.By Larry Larder and Jeff WiersmaHerman Miller Inc., Michigan, U.S.A. Herman Miller Inc. transformed theresidential furniture industry as Ameri-ca’s first proponent of modern design,beginning in the early 1930s throughcollaborations with iconic figures likeGilbert Rohde, George Nelson, Charlesand Ray Eames, Isamu Noguchi andAlexander Girard. Later the companytransformed the modern office withthe world’s first open-plan officesystems in the 1960s and the conceptof ergonomic office seating in 1976with the introduction of the Ergon®chair, followed by the Equa® chair in1984. In 1994, the company launched The TriFlex back that automatically adjusts to each user was developed as a single composite plasticthe groundbreaking Aeron® chair. structure using analysis to determine the coupled response of the back and its supporting spine.Founded in 1923, the company is oneof the oldest and most respectednames in American design. It has office seating offering ergonomicbeen recognized as a design leader, comfort for a wide range of body typesreceiving the Smithsonian’s “National and postures and easy adjustabilityDesign Award.” Dozens of its designs for fit and feel. The cost also neededare in the permanent collections at to be kept as low as possible throughmajor museums worldwide, including reduced part counts and effective usethe New York Museum of Modern Art, of structural materials, developedthe Whitney Museum, the Henry Ford completely under Design for theand the Smithsonian Institution. Environment (DFE) protocols. As one of the leaders in high- Given these many complex andperformance office furniture, Herman potentially conflicting requirements,Miller set its sights in 2000 on the long- developing the chair through cyclesneglected and potentially lucrative of trial-and-error physical testingmid-priced segment of the market, was considered impractical becauserepresenting half of all office chairs the approach is expensive, time-sold worldwide. The goal was to consuming, and limits the number of Herman Miller’s new award-winning Mirra office chairdevelop the Mirra chair as an entirely TM design alternatives to be evaluated. was developed through virtual prototyping usingnew reference point for mid-priced Engineers needed a way to optimize ANSYS software.14 ANSYS Advantage • Volume I, Issue 1, 2007
  17. 17. CONSUMER PRODUCTSthe design early in the developmentby investigating a wide range ofpossibilities at that stage. Thesechallenges were met through the useof virtual prototyping, in which “what-if” scenarios can be readily studied inthe computer and hardware testing ismore of a verification of the design atthe end of the cycle. One of the key virtual prototypingtechnologies selected was ANSYSstructural analysis software, used ANSYS Structural software played a key role in the development of the cantilever leaf spring andas the primary tool for determining moving fulcrum tilt mechanism.stress and deflection on every partof the chair. Engineers routinely usedANSYS DesignSpace to develop for developing similar mechanisms in engineers to consolidate parts intomajor components such as the base, other chair models. integral modules, thus minimizing partarms, and pedestal. For more complex Another major feature of the chair counts and lowering manufacturinganalysis, ANSYS DesignSpace models is a “passively adjustable” polypropy- costs significantly. Due to these andwere used by an analyst as the basis lene back. In contrast to conventional other cost efficiencies, product marginsfor detailed simulation with ANSYS rigid-back chairs, the pliable TriFlex TM for the Mirra have met target objec-Structural software. back design provides the proper tives. In terms of market acceptance, ANSYS Structural played an deflection according to the user’s the chair has consistently exceededimportant role in the development of posture and movements. This concept the company’s targets for orders andone of the chair’s key assemblies: a evenly distributes seating forces, thus shipments.cantilever leaf spring and moving ful- reducing load concentrations and Introduced in 2003, the Mirra chaircrum tilt mechanism that provide fatigue. Engineers used ANSYS received the Gold Award in the Best ofresistive force so that a person can Structural software to determine the NeoCon industry competition. It waslean back comfortably. Torque curves coupled response of the back and its named by FORTUNE magazine as onewere generated to represent the force supporting spine based on the material of the “Best Products of the Year” andrequired to support various body types characteristics of each part together received the Chicago Athenaeumin three seat positions: upright, fully with the size and geometric pattern of Museum of Architecture and Design’stilted and midway. The analyst wrote a the perforated back. Analysis was Good Design Award. The goal of thetext script file to simulate a range used extensively to engineer a single Mirra chair was to set a new referenceof spring and fulcrum combinations composite plastic structure that deliv- point for the mid-price seatingto operate within this torque-curve ered the required coupled deflection market in terms of ergonomics anddesign envelope. Output from ANSYS response, reduced the parts count for adjustability. Simulation with ANSYSsoftware included spring deflection the assembly and conformed to the software certainly allowed Hermanand stress distributions, giving DFE environmental criteria. Miller to meet these objectives withengineers insight into each design so With the aid of simulation, Herman advanced technology that could bethat they could select and refine the Miller developed an optimal chair integrated easily into its productconfiguration that worked best. The design that delivered the required development process. Rather thanresult was an optimal mechanism that functionality while maintaining the merely fix problems toward the end ofprovided the range of torque required company’s high quality standards of the development cycle, simulationwith only a few simple adjustments. wear and reliability. Prototype testing was used to guide the design. As aGuided by the simulation, the design time was minimized, with a physical result, the Mirra is probably one ofmet the company’s objectives of com- mock-up used to verify the functional Herman Miller’s most successful andfort and adjustability. Moreover, the performance established through highly engineered products. Itext script file will be used as a basis analysis. Simulation also ANSYS Advantage • Volume I, Issue 1, 2007 15
  18. 18. PHARMACEUTICALSTransport of Fragile GranulesPneumatic conveying systems in the pharmaceuticalindustry can lead to unwanted particle breakup.By Pavol Rajniak and Rey Chern, Pharmaceutical CommercializationTechnology, Merck & Company, Inc.; U.S.A., Kumar Dhanasekharan, ANSYS,Inc.; Csaba Sinka and Neil MacPhail, Merck Sharp and Dohme, U.K. Pneumatic conveying systems are used at pharmaceu-tical manufacturing sites to transport granular materials.These materials — the active ingredient and various inactiveingredients — are combined to produce granules and then Laser diffraction Inlet for dryare transported to tablet presses, where pills are formed. measurement powder from Regulated air To vacuum chamber vibrating pressure inletGranule attrition, in which the particles suffer wear as a feeder plateresult of collisions and friction, can occur during thetransport of materials. Even for a dilute mixture, attrition can Flexible tubereduce characteristic particle sizes by as much as 50 per-cent [1] leading to a deterioration in the granule propertiesand potentially compromising the quality attributes of the The Malvern Mastersizer particle size analyzer and its dry powder feeder (DPF)pharmaceutical product. Experimental and theoreticalstudies to understand the mechanical impact of conveying Another mimics well-defined stress conditions in simpleon granules are needed so that formulations, the processing setups to identify basic attrition mechanisms [3–5].parameters and the pneumatic conveying systems can be The current study demonstrates the use of a moreoptimized to avoid problems at the large scale. To address fundamental and scientific approach to study particle attri-attrition phenomena, different experimental and theoretical tion [6]. It incorporates an experimental program with CFDapproaches have been followed. One experimental modeling of the gas–solid system. Experiments are carriedapproach has been carried out at various bends, providing out on the Malvern Mastersizer DPF, a laboratory-scale drystress conditions closely related to industrial processes [2]. powder feeder and particle size analyzer from Malvern Instruments, U.K. The Eulerian granular multiphase model is used with the new population balance (PB) module in FLUENT 6.3 software to simulate the motion of the solid and gas phases and attrition within the device. The numerical model makes use of a semi-empirical expression for computing the breakage of solid particles. This expres- sion involves the impact velocity of solid phase particles as they strike the wall and a small set of parameters that are obtained by fitting the model to experimental data. The particle size distribution (PSD) is an important characteristic of a powder system because it plays a role in the final product quality. It is routinely measured by laser diffraction using bench-top equipment such as the Malvern Mastersizer. The powder under test is fed using a vibrating feeder and then suspended by a jet of compressed air whose pressure can be varied. Increasing the air jet pressure produces a finer PSD as a consequence of more extensive attrition. Below the suspending jet but upstream of the laser diffraction measurement chamber is a pipe bend, a key part of this lab-scale pneumatic conveying system. It generally is recognized that during pneumatic conveying, the particles experience extensive impact loads at the bends because the flow direction is changing [2]. For Contours of the solid phase volume fraction with solid phase velocity this reason, the initial CFD calculations were of the bend vectors (left), and Sauter mean diameter (right) in the vicinity of the bend for an inlet jet pressure of 1.5 barg, inlet gas velocity of 30 m/s, where the particle size distribution could be computed average inlet granule diameter of 57.8 µm and granular material using the population balance module. density of 1200 kg/m3. The results show the solids collecting near the outer wall of the bend and lowering the Sauter mean diameter For the experiments, granule samples were analyzed at because of increased attrition. different inlet air jet pressures ranging from 0.5 to 2 barg16 ANSYS Advantage • Volume I, Issue 1, 2007
  19. 19. PHARMACEUTICALS(bars gauge). Moments m0, m1, m2, and m3 of the original 60PSDs were evaluated using the relationship: 50 40in which ni is the volumetric number of particles in classi having characteristic size (diameter) Li. The moments are Experimental datacompared in Table 1 for the range of jet pressures tested. All 30 CFD-PB: v0 = 0.5, kv = 2.0e+9 CFD-PB: v0 = 1.0, kv = 2.0e+9of the moments increase with increasing inlet jet pressure as CFD-PB: v0 = 1.0, kv = 3.1e+9a consequence of attrition, with the exception of m3. This 20moment is a relative measure of the preserved volume of 0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00granules, so should be independent of the inlet pressure. A Inlet jet pressure Pin [barg]comparison of the Sauter mean diameter, d32 = m3 /m2, widely Comparison of the Sauter mean diameter computed from experimentalused to characterize a PSD, also is presented in the table. As data with that predicted by the CFD model using three different sets ofexpected, the increased attrition at higher jet pressures is in fitting parametersevidence as the Sauter mean diameter steadily drops. 6.0e-5 Pin (barg) 0.5 1.0 1.3 1.5 2.0 5.5e-5 m0 .10-15 [ #/m3] 7.744 9.982 13.010 14.442 20.468 5.0e-5 m1 .10-9 [m/m3] 6.164 8.301 11.198 12.884 17.762 4.5e-5 m2 .10-4 [m2/m3] 3.304 3.978 4.672 5.120 5.950 m3 [m3/m3] 1.910 1.910 1.910 1.910 1.910 4.0e-5 Pin = 0.50 barg Pin = 1.00 barg d32 .106 [m] 57.81 48.01 40.88 37.30 32.10 3.5e-5 Pin = 1.50 barg Pin = 2.00 bargTable 1: First moments of the particle size distribution for a range of experimental 3.0e-5inlet pressures 2.5e-5 CFD results from a 2-D model of the bend were used to 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14provide insight on the behavior of the solids as they travel Curve length of the lower wallthrough this region of the dry powder feeder. In particular, Calculated Sauter diameter of solid particles along the lower wall of the powder feeder at different inlet jet pressures, illustrating the increasedthey show that the velocity gradients are highest in the attrition at higher pressuresbend. Contours of the Sauter mean diameter and volumefraction of solids, also computed using the CFD model,show a significant decrease of the particle diameter at the models can be employed after fitting to experimental databend, suggesting increased attrition in this region. X-Y plots for predicting attrition and breakage in large-scale pneumaticof the solid velocity magnitude and of d32 along the lower conveying systems and to assess the suitability of a givenwall provide further insight into the flow and breakage batch of granular material for larger scale processing. Iphenomena in the process. These plots also indicate Referencesbreakage around the bend of the transport pipe, suggestingthat improvements to the transport system are needed. [1] Chapelle, P.; Abou-Chakra, N.; Christakis, N.; Bridle, I.; Patel, M. K.; Baxter, J.; Tuzun, U.; Cross, M.: Numerical Predictions of ParticleCurrently, Merck and ANSYS are continuing studies Degradation in Industrial-scale Pneumatic Conveyors. Powderthat incorporate multiple breakage in 3-D geometries Technology 143-144: 321–330, further evaluate both lab-scale and plant-scale powder [2] Kalman, H.: Attrition of Powders at Various Bends During Pneumatichandling equipment. Conveying. Powder Technology 112: 244 – 250, 2000. Parametric studies also were performed to investigate [3] Salman, A. D.; Hounslow, M. J.; Verba, A.: Particle Fragmentation inthe impact of different model parameters on the extent of Dilute Phase Pneumatic Conveying. Powder Technology 126:breakage and resulting shape of the PSDs, as characterized 109–115, the PSD moments. The particle breakup model satisfac- [4] Zhang, Z.; Ghadiri, M.: Impact Attrition of Particulate Solids: Part 2.torily predicted the experimental Sauter mean diameter, but Experimental Work. Chem. Eng. Sci. 57: 3671–3686, 2002.the lower moments, m0 and m1, were under-predicted. This [5] Gentzler, M.; Michaels, J. N.: Impact Attrition of Brittle Structuredcould be due to breakage that results from an erosion Particles at Low Velocities: Rigorous Use of a Laboratory Vibrationalmechanism similar to that reported in the literature for a Impact Tester. Chem. Eng. Sci. 59: 5949–5958, 2004.stirred ball milling application [7]. [6] Rajniak, P.; Dhanasekharan, K.; Sinka, C.; MacPhail, N.; Chern, R.; The methodology illustrated here allows engineers to Fitzpatrick, S.. Modeling and Measurement of Granule Friability. Fifthcorrelate the observed changes in particle size with the World Congress on Particle Technology (Conference Proceedings CDshear forces or impact velocities within the system. It Vol.2): 23-27, Orlando, FL, U.S.A., April assumed that analogous physically based models [7] Diemer, R. B.; Spahr, D. E.; Olson, J. H.; Magan R. V.: Interpretation ofcombining properties of the gas–solid flow with the PB Size Reduction Data via Moment Models. Powder Technology 156: 83–94, ANSYS Advantage • Volume I, Issue 1, 2007 17