Computational Fluid Dynamics: Getting Started Quickly With ANSYS CFX 18 Through Simple Examples PDF
Preview Computational Fluid Dynamics: Getting Started Quickly With ANSYS CFX 18 Through Simple Examples
Stefan Lecheler Computational Fluid Dynamics Getting Started Quickly With ANSYS CFX 18 Through Simple Examples Computational Fluid Dynamics Stefan Lecheler Computational Fluid Dynamics Getting Started Quickly With ANSYS CFX 18 Through Simple Examples StefanLecheler FacultyofMechanicalEngineering BundeswehrUniversityMunich Neubiberg,Germany ISBN978-3-658-38452-4 ISBN978-3-658-38453-1 (eBook) https://doi.org/10.1007/978-3-658-38453-1 ThisbookisatranslationoftheoriginalGermanedition“NumerischeStrömungsberechnung”byLecheler,Stefan, publishedbySpringerFachmedienWiesbadenGmbHin2018.Thetranslationwasdonewiththehelpofartificial intelligence(machinetranslationbytheserviceDeepL.com).Asubsequenthumanrevisionwasdoneprimarilyin termsofcontent,sothatthebookwillreadstylisticallydifferentlyfromaconventionaltranslation.SpringerNature workscontinuouslytofurtherthedevelopmentoftoolsfortheproductionofbooksandontherelatedtechnologies tosupporttheauthors. #TheEditor(s)(ifapplicable)andTheAuthor(s),underexclusivelicensetoSpringerFachmedienWiesbaden GmbH,partofSpringerNature2022 Thisworkissubjecttocopyright.AllrightsaresolelyandexclusivelylicensedbythePublisher,whetherthe wholeorpartofthematerialisconcerned,specificallytherightsoftranslation,reprinting,reuseofillustrations, recitation,broadcasting,reproductiononmicrofilmsorinanyotherphysicalway,andtransmissionorinformation storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now knownorhereafterdeveloped. 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Theregisteredcompanyaddressis:Abraham-Lincoln-Str.46,65189Wiesbaden,Germany Preface In the meantime, commercial flow calculation programs such as CFX, FLUENT, and STAR-CDhavereachedsuchahighlevelofdevelopmentintermsofflexibility,accuracy, and efficiency that they are used for very many flow problems in industrial applications. Withoutthem,efficientdevelopmentofnewvehicles,aircraft,engines,andturbineswould nolongerbepossible. Forthisreason,developmentengineersmustnowadaysbeproficientintheuseofCFD (computationalfluiddynamics)programs.Sinceevensmallinputerrorscanhaveamajor impact on the calculation result, these must be avoided at all costs. This book aims to contributetothisand,inadditiontothemostimportanttheoreticalprinciples,aboveallto providenumeroustipsandexperiencesrelevanttopractice. Thisbookoriginatesfromthelecture“NumericalFlowCalculation,”whichisofferedin the master’s program in computer aided engineering at Bundeswehr University Munich. Withinthisprogramstudentslearnbymeansofpracticalexerciseswithacommercialflow calculationprogramhowtouseit,whichtheoryisbehinditandhowtointerprettheresults. Theirsuggestionswereincorporatedintothebook.Forexample,complicatedmathematics was avoided as far as possible and great importance was attached to clarity and comprehensibility. Iwouldliketothankallsupervisorsandcolleagueswhosupportedmeinmyworkinthe fieldofcomputationalfluiddynamicsattheInstituteofSpaceSystemsattheUniversityof Stuttgart,atthevonKarmanInstituteinBrussels,intheThermalMachinesLaboratoryat ABB Turbo Systems in Baden/Switzerland, in gas turbine development at ALSTOM Baden/Switzerland,andatBundeswehrUniversityMunich. Iamverypleasedthatthefourtheditioncannowbepublished.Init,afewcorrections have been made, and the three exercise examples have been adapted to the latest version ANSYS18.1. The CAD files are now read directly as in real applications. These are available on the Internet at www.unibw.de/mb/institute/we5/we51/downloads/ downloads-start. IwouldliketothankthecompaniesANSYSandISimQforprovidingmewithexample images that show the power of modern flow calculation programs. I would also like to v vi Preface thank Mr. Zipsner and the mechanical engineering editorial office of Springer Vieweg Verlagfortheirgoodsupport. BadToelz,July2017,StefanLecheler Neubiberg,Germany StefanLecheler Symbol directory Symbol Unit Designation A m2 Area,surface a m/s2 Acceleration a m/s Speedofsound CFL – Courant-Friedrichs-LevyNumber c J/kg/K Specificheatcapacityatconstantvolume v c J/kg/K Specificheatcapacityatconstantpressure p dx,dy,dz M SidesurfacesofthevolumeelementdV E_ Y/s Energyflux e J/kg Specificinternalenergy ε m2/s3 Turbulentdissipation F N Force F,G,H – FlowvectorsinCartesiancoordinates Fb,Gb,Hb – Flowvectorsincurvilinearcoordinates g m/s2 Accelerationduetogravity h J/kg Specificenthalpy I – Unitmatrix I_ N/s Momentumflux i,j,k – Meshpointindexinthethreespatialdirections k m2/s2 Turbulentkineticenergy λ W/m/K Thermalconductivitycoefficient Ma – Machnumber m kg Mass m_ kg/s Massflow NBC – Numericalboundaryconditions ∇→ – Divergence n – Normaldirection (continued) vii viii Symboldirectory Symbol Unit Designation μ Pas Dynamicviscosity ω m2/s3 Turbulentfrequency PBC – Physicalboundaryconditions p Pa Print ϕ – Potential Q – SourceterminCartesiancoordinates Qb – Sourcetermincurvilinearcoordinates Q_ W Heatflux q_ W/kg Specificheatflux R J/kg/K Gasconstant ρ kg/m3 Density S J/K Entropy T K Temperature t,τ s Time U – ConservationvectorinCartesiancoordinates,alsogeneral flowquantity Ub – Conservationvectorincurvilinearcoordinates u,v,w m/s Velocitycomponentsinx-,y-,z-direction V,dV m3 Volume,volumeelement W_ W Power x,y,z m Cartesianspatialcoordinates ξ,η,ζ – Curvilinearspatialcoordinates Index Designation i,j,k Spatialdirections x,y,z x-,y-,z-direction n Timelevel t Total w Wall + Positiveeigenvalue - Negativeeigenvalue Contents 1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1 AimofThisBook. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 TasksoftheNumericalFlowCalculation. . . . . . . . . . . . . . . . . . . . . 2 1.3 StructureoftheBook. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 2 ConservationEquationsofFluidMechanics. . . . . . .. . . . . . . . .. . . . . . . 13 2.1 AimofThisChapter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2.2 DerivationoftheConservationEquations. . . . . . . . . . . . . . . . . . . . . 14 2.3 Navier-StokesEquations. . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . 24 2.4 SimplificationPossibilities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 3 DiscretizationoftheConservationEquations. . . . . . . . . . . . . . . . . . . . . . 47 3.1 AimofThisChapter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 3.2 WhatDoesDiscretizationMean?. . . . . . . . . . . . . . . . . . . . . . . . . . . 48 3.3 SpatialDiscretization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 3.4 TimeDiscretization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 3.5 DifferenceEquations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 4 ComputationalMeshes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 4.1 AimofThisChapter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 4.2 Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 4.3 StructuredMeshes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 4.4 UnstructuredMeshe. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 4.5 MeshAdaptation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 5 SolutionMethods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 5.1 AimofThisChapter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 5.2 Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 5.3 CentralMethods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 5.4 UpwindMethods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 5.5 High-ResolutionMethods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 5.6 ComparisonoftheMethods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 ix x Contents 6 TypicalWorkflowofaNumericalFlowCalculation. . . . . . . . . . . . . . . . . 113 6.1 AimofThisChapter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 6.2 Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 6.3 GenerationoftheCalculationArea(Geometry). . . . . . . . . . . . . . . . . 115 6.4 GenerationoftheMesh(Meshing). . . . . . . . . . . . . . . . . . . . . . . . . . 117 6.5 PreparationoftheFlowCalculation(Setup). . . . . . . . . . . . . . . . . . . . 119 6.6 FlowCalculation(Solution). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 6.7 Evaluation(Results). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 6.8 Validation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 6.9 IntroductiontotheExerciseExamples. . . . . . . . . . . . . . . . . . . . . . . . 122 6.10 TheANSYSWORKBENCHWorkingEnvironment. . . . . . . . . . . . . 123 7 ExampleAirfoilFlow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 7.1 GenerationoftheCalculationArea(Geometry). . . . . . . . . . . . . . . . . 127 7.2 GenerationoftheMesh(Meshing). . . . . . . . . . . . . . . . . . . . . . . . . . 129 7.3 PreparationoftheFlowCalculation(Setup). . . . . . . . . . . . . . . . . . . . 133 7.4 CalculationoftheFlow(Solution). . . . . . . . . . . . . . . . . . . . . . . . . . 142 7.5 Evaluation(Results). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146 8 ExampleInternalPipeFlow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155 8.1 GenerationoftheCalculationArea(Geometry). . . . . . . . . . . . . . . . . 155 8.2 GenerationoftheMesh(Meshing). . . . . . . . . . . . . . . . . . . . . . . . . . 159 8.3 PreparationoftheFlowCalculation(Setup). . . . . . . . . . . . . . . . . . . . 162 8.4 CalculationoftheFlow(Solution). . . . . . . . . . . . . . . . . . . . . . . . . . 166 8.5 Evaluation(Results). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168 9 ExampleDoubleTubeHeatExchanger. . . . . . . . . . . . . . . . . . . . . . . . . . 173 9.1 GenerationoftheCalculationArea(Geometry). . . . . . . . . . . . . . . . . 173 9.2 GenerationoftheMesh(Meshing). . . . . . . . . . . . . . . . . . . . . . . . . . 174 9.3 PreparationoftheFlowCalculation(Setup). . . . . . . . . . . . . . . . . . . . 180 9.4 CalculationoftheFlow(Solution). . . . . . . . . . . . . . . . . . . . . . . . . . 185 9.5 Evaluation(Results). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 10 ExampleParameterVariation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195 AnswerstotheTargetControl. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205 Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
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