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1、ANSYSFLUENT优化技术培训 姓名 宋述军公司 安世亚太科技 北京 有限公司 Preface ThereleaseoftheadjointsolverinFluent13istheculminationofseveralyearsofR Deffort Thisprojectwasrisky buttherewardsaregreat bothforANSYSanditsclients Therewereanumberoffalsestartsanddead ends Writinganadjointsolverthatmeetstheneedsoftheengineeringcommu
2、nityisnotatrivialtask Wearepleasedtohavecomesofar andlookforwardtogoingmuchfurther KeyIdeas Fundamentals KeyIdeas Fundamentals FLOWSOLVER High level system viewofaconventionalflowsolver HowarechangestoKEYOUTPUTSDEPENDENTonchangestotheINputs KeyIdeas Fundamentals Flowsolutionq andtheinputstotheproble
3、mc Output ResidualsoftheNavier Stokesequations LinearizedNavier Stokes EngineeraparticularlinearcombinationoflinearizedNSequations introducemultipliers Topleveladjointsolveralgorithm quasi NewtonschemeSolveusingAMGInvolvesafamiliarprocessSolutionadvancementcontrols Courantnumber under relaxationResi
4、duals iterationsRoughlythesameeffortasaconventionalflowsolution KeyIdeas AdjointEquations Thisinnocent lookingsystemofequationsisattheheartoftheadjointsolver Constructandsolveanadjointproblemtogetahelpersolution Approximatelinearizationwithpseudo timestepintroduced Similartooriginalflowsolver buttra
5、nsposed Updatetotheadjointsolution SystemJacobian transposed Derivativeofachosenobservablewithrespecttotheflowsolution KeyIdeas Workflow KeyIdeas ShapeSensitivity Shapesensitivity Sensitivityoftheobservedvaluewithrespectto boundary gridnodelocations DragsensitivityforNACA0012 KeyIdeas GradientAlgori
6、thm Optimization Firstorderestimateofthechange KeyIdeas MeshMorphing Flow KeyIdeas MeshMoprhing Actualchange3 1DP 213 8Totalimprovementof8 KeyIdeas MeshAdaptation AdjointsolutionDragsensitivity BaselineMesh AdaptedMesh AdaptedMeshDetail KeyIdeas Usage Theadjointsolverisabetaaddonfeaturetobereleasedw
7、ithallFluent13packages Documentationwillbeavailableonlineviatheuserservicescenter TheoryUsageTutorialCasestudyFunctionalityisactivatedbyEnablingbetafeatures LoadingtheadjointsolveraddonmoduleAnewmenuitemisaddedatthetoplevel TUIentriesunderadjoint Usage Overview adjoint controlsmorphing reporting mon
8、itors observable run GUIFollowascloseaspossiblesamedesignlayoutasFluentsolverSpecifyobservableAdjointsolutionadvancementcontrolsResidualmonitorsInitializationanditerationPost processing contours vectors ResultsreportingMesh morphingwithpre calculationofexpectedchangeinobservable Usage Overview Usage
9、 Overview ANSYS FluentflowsolverhasverybroadscopeAdjointisconfiguredtocomputesolutionsbasedonsomeassumptionsSteady incompressible laminarflow Steady incompressible turbulentflowwithstandardwallfunctions First orderdiscretizationinspace Frozenturbulence TheprimaryflowsolutiondoesNOTneedtoberunwiththe
10、serestrictionsStrongevidencethattheseassumptionsdonotunderminetheutilityoftheadjointsolutiondataforengineeringpurposes Fullyparallelized GradientalgorithmforshapemodificationMeshmorphingusingcontrolpoints Adjoint basedsolutionadaption Usage Overview ModellimitationsNoporousmediaNoMRFNocompressibilit
11、yNoheattransfer Twotypesofmodeling relatedmessagesmaybeprintedintheconsoleProvidesdetailsofthedifferencesbetweenhowtheadjointsolverimplementationistreatingtheproblemincomparisontotheconventionalflowsolver WarningDifferenceisnotfatal Adjointsolvercanexecute Maydetractfromqualityofadjointresults Error
12、Modelsusedintheconventionalsolverareincompatiblewiththeadjointsolver Adjointsolvercannotberun Usage flowaroundcylinder Contoursofvelocitymagnitude Contoursofvelocitymagnitude TUI define models addon moduleFLUENTAddonModules 0 None1 MHDModel2 FiberModel3 FuelCellandElectrolysisModel4 SOFCModelwithUnr
13、esolvedElectrolyte5 PopulationBalanceModel6 AdjointSolverEnterModuleNumber 0 6 Usage Observables Availableobservables Forceinspecifieddirection Directioninwhichforceistoberesolved Contributingwalls Observabletypeselection Writevalueofobservabletofile Printvalueofobservableinconsole Totalpressuredrop
14、 InitializingDiscreteAdjointSolver Done Observedvalue 1 337968765e 03 n Usage Controls SolutionAdvancementControls Courantnumber SmallervaluestabilizesinnerAMGiterations butresultsinmoreouteriterations Enablepreconditioning Usuallyrequiredforturbulentflowproblems Artificialcompressibility Largervalu
15、estabilizesinnerAMGiterations butresultsinmoreouteriterations Stabilizationfactor Increasethisvaluetostabilizethecalculationinregionsofstrongshear Alargervalueimpliesalessaccurateadjointsolution Under Relaxationfactors Thesefactorsplaythesameroleastheconventionalflowsolverunder relaxationfactors Tol
16、eranceforconvergenceoftheinnerAMGiterations MaximumnumberofAMGiterationstobeattempted PrinttheresidualsoftheAMGiterationsintheconsole Usedtoverifythattheinneriterationsareconverging Usage Monitors Residualmonitorsandconvergencecriteria Defineconvergencecriteriaforadjointequations Whetherornotanequationistobecheckedforconvergence Samebehaviorasconventionalflowsolver Residualsplottedinspecifiedwindow Usage Iterating Initialization Iteration Initializetheadjointsolutionfieldtozeroeverywhere Maximum
