CFX_Multiphase_120_WS05_Interphase_Mass_Transfer_f.ppt

Workshop5InterphaseMassTransferforMulticomponentFluids CFXMultiphasefortheNuclearIndustry MulticomponentMassTransferforaSteamJet ThisexampleshowshowonemaysetupmulticomponentmasstransferusingasourceandsinkapproachwithsubdomainsItsimulatesthehigh speedflowofwetsteamintoairwhereitcanmixwithdryairandeithercondenseontoliquiddropletsorevaporateliquidwaterdropletsThisexampledemonstrates UseoftheIAPWSMaterialLibraryforpropertiesofliquidwaterandsteamMulticomponentmultiphasemasstransferwithsourcesandsinksTreatmentoflatentheateffectsUseoflinearizationcoeffcientsforuserdefinedsourcestohelpaidconvergence ImportingtheMesh Tosavetime anaxisymmetricmeshwithasingleelementinthethetadirectionwillbeusedStartCFX Preandcreateanewsimulation File NewCase General IntheOutline right clickonMeshandselectImportMesh CFXMesh thenchoosesteam jet gtmfromtheinput filesfolderforthiscourseandclickOpen ComputationalMesh CCLFileImportforPredefinedExpressions Inordertoshortentheset uptimeforthistutorial CCLfileswhichsetupexpressionsforvariousparametersfortheinterphasemasstransferaswellasadditionalvariableswhichwillbedefinedforthedomainwillbeimportedFromtheFilemenu selectImportCCL enterthesteam jet expressions cclasthefilename locatedintheinput filesfolderforthiscourse andclickOpen Thisfiledefinesexpressionsrequiredforsettingupthefollowingdata Liquid gasinterfaceInterphasediffusivetransportcoefficientHeatsofvaporizationLiquid gasmasstransferforwaterContinuitylinearizationwithrespecttoP LocalfalsesteplinearizationoftheIPMTTimestepprofile ImportedExpressions CCLFileImportforAdditionalVariables FromtheFilemenu selectImportCCL entersteam jet additional variables cclasthefilename locatedintheinput filesfolderforthiscourse andclickOpen Thisfiledefinesthefollowingadditionalvariables PressurelinearizationcoefficientPCoefWaterIPMTfluxliquidtogasWaFluxLGWaterIPMTfluxgastoliquidWaFluxGLLocalIPMTfalsetimestepFalseDtSaturationtemperatureforpostprocessing SatTempSaturationpressureforpostprocessing SatPresLatentheatatsaturationforpostprocessing SatLHeat LoadingMaterialsfromtheIAPWSLibrary IntheOutline right clickonMaterialsandselectImportLibraryData ClickthebrowsebuttonnexttoFiletoImport TheImportCCLdialogboxappears UnderImportMethod selectAppend ThisoptionsappendstheCCLchangestotheexistingcase SelectMATERIALS iapws cclfromtheetc materials extradirectoryandclickOpen IntheSelectLibraryDatatoImportdialogbox expandWetSteamandselectSteam3vl ClickOK IntheOutlinetreeview expandMaterialstoconfirmthatSteam3l Steam3v andSteam3vlhavebeenaddedtothelist DefiningaVariableCompositionMixture Gas Right clickonMaterialsandselectInsert MaterialNamethenewmaterial GasmixtureOntheBasicSettingstab settheOptiontoVariableCompositionMixtureandselectAirIdealGasandSteam3vasthetwocomponentsintheMaterialsList holdtheCTRLkeydowntopermitmultipleselections ClickOKtocreatethemixture DefiningaFixedCompositionMixture Liquid Right clickonMaterialsandselectInsert MaterialNamethenewmaterial LiquidmixtureOntheBasicSettingstab settheOptiontoFixedCompositionMixtureandSteam3lasthesinglecomponentintheMaterialsListSettheMassFractionforSteam3lto1 0ClickOKtocreatethemixtureThissimulationwillmodeltransferofmassfromapureliquidphasetoagasphasecontainingairandwatervaporwhichiswhythetwomaterialshavebeencreatedasspecified FluidDefinition Gas EdittheDefaultDomainOntheBasicSettingstab highlightFluidDefinition1anddeleteit CreateanewFluidDefinitionnamedGasandassignthematerialGasmixturetoit SettheMorphologyoptiontoContinuousFluid FluidDefinition Liquid CreateanewFluidDefinitionnamedLiquidandassignthematerialLiquidMixturetoit SettheMorphologyoptiontoDispersedFluidandsettheMeanDiametertotheexpressionliqLengthdefinedinthecclfilethatyouimported YouwillneedtoclickontheEnterExpressioniconnexttotheMeanDiameterentryboxtoenableentryofanexpression FluidModels OntheFluidModelstab settheHeatTransferandTurbulenceoptiontoFluidDependentOntheFluidModelstabunderAdditionalVariableModels AdditionalVariable selectFalseDtandselecttheFalseDtcheckbox MakesurethatAdditionalVariableModels AdditionalVariable FalseDt OptionissettoFluidDependent RepeattheprevioustwostepsfortherestoftheAdditionalVariables PCoef SatLheat SatPres SatTemp WaFluxGL WaFluxLG FluidSpecificModels Gas OntheFluidSpecificModelstab selectGasinthelistbox thenapplythefollowingsettingsSettheHeatTransferOptiontoTotalEnergySettheTurbulenceOptiontok EpsilonUnderComponentModels selectAirIdealGasandsettheOptiontoConstraintUnderComponentModels selectSteam3vandsettheOptiontoTransportEquation EnablethetoggletosettheKinematicDiffusivity ClicktheExpressioniconandenterthepredefinedexpressionKinDiffUnderAdditionalVariableModels enablethetoggleforPcoefandsettheAdd Var ValuetothepredefinedexpressiondFLUXwadp Constraint FluidSpecificModels Liquid OntheFluidSpecificModelstab selectLiquidinthelistbox thenapplythefollowingsettingsSettheHeatTransferOptiontoTotalEnergySettheTurbulenceOptiontoDispersedPhaseZeroEquationUnderAdditionalVariableModels enablethetoggleforallvariablesandsetthevaluestothefollowingpredefinedexpressionsafterclickingtheExpressioniconforeachentry FalseDt DtFalseMfPcoef dFLUXwadpSatLheat HtVapwaSatPres VpWatSatTemp SatTWaFluxGL FLUXwa1WaFluxLG FLUXwa2 FluidPairModels OntheFluidPairModelstab enabletheSurfaceTensionCoefficienttoggleandentertheexpressionsrfTenCoefafterclickingtheExpressioniconSettheInterphaseTransferOptiontoParticleModel UnderMomentumTransfer settheDragForceOptiontoSchillerNaumannSettheHeatTransferOptiontoRanzMarshallClickOKtocompletethedefinitonoftheDomain SubdomainGastoLiq GasContinuitySource Youwillinputyourowncustommasstransfermodelusingsourcesformass massfraction andenergyforasubdomainwhichcomprisestheentiremodelClicktheSubdomainiconandnamethesubdomainGastoLiq Thesourcesforthissubdomainwillbedefinedinamannerconsistentforcondensation OntheBasicSettingstab settheLocationtoB26OntheFluidSourcestab highlightGasandenablethetoggle NexthighlightContinuityandenablethattoggleSetthefollowingvalues FluidMassSource Liquid WaFluxGLMCF EnergySinkOptionenabledandsettoSpec MassFrac andLoc Temp MassSourceVolumeFractionCoefficientenabledandsetto Gas density DtFalseMf notethereshouldbeaminussignbeforeGas densityinthisexpression Steam3v mfto1 TemperaturetoGas T TurbulenceEddyDissipationtoGas ed TurbulenceKineticEnergytoGas ke andtheCartesianVelocityComponentstoGas Velocityu Gas Velocityv andGas Velocityw SubdomainGastoLiq SteamMassFractionSource Youwilldefineadummysteammassfractionsourceof0justtoenablesettingalinearizationcoefficientOntheFluidSourcestab withGasstillselected highlightSteam3v mfandenablethetoggleSetthefollowingvalues Sourceto0 0 kg m 3 s EnabletheSourceCoefficienttoggleandsetittothepredefinedexpressiondFLwadYGNote thesourcecoefficienthereisdefinedforconvergencepurposes ithelpsenforceboundedness SubdomainGastoLiq LiquidContinuitySource OntheFluidSourcestab highlightLiquidandenablethetoggle NexthighlightContinuityandenablethattoggleSetthefollowingvalues FluidMassSource Liquid WaFluxGLMassSourceVolumeFractionCoefficientenabledandsetto Liquid density DtFalseMf notethereshouldbeaminussignbeforeLiquid densityinthisexpression TemperaturetoGas TCartesianVelocityComponentstoGas Velocityu Gas Velocityv andGas Velocityw SubdomainGastoLiq LiquidEnergySource Youwilldefinealiquidenergysourcetoaccountforthelatentheatduetophasechange Thelatentheatisassumedtobetransferredtotheliquid OntheFluidSourcestab withLiquidstillselected highlightEnergyandenablethetoggleSetthefollowingvalues Sourcetotheexpression Liquid WaFluxGL HtVapwaEnabletheSourceCoefficienttoggleandsetittotheexpression Liquid vf Liquid density Liquid Cp DtFalseMf notetheminussignprecedingLiquid vfinthisexpression ClickOKtocompletethedefinitionoftheSubdomain SubdomainLiqtoGas GasContinuitySource Youwildefineasecondsubdomaintoaccountforthepossibilitythatvaporizationoccurs ThemasssourcesaredefinedsothatonlyoneprocesswillapplyataparticularlocationinthedomainClicktheSubdomainiconandnamethesubdomainLiqtoGas OntheBasicSettingstab settheLocationtoB26OntheFluidSourcestab highlightGasandenablethetoggle NexthighlightContinuityandenablethattoggleSetthefollowingvalues FluidMassSource Liquid WaFluxLGSteam3v mfto1TemperaturetoSatTTurbulenceEddyDissipationtoGas edTurbulenceKineticEnergytoGas keCartesianVelocityComponentstoLiquid Velocityu Liquid Velocityv andLiquid Velocityw SubdomainLiqtoGas LiquidContinuitySource OntheFluidSourcestab highlightLiquidandenablethetoggle NexthighlightContinuityandenablethattoggleSetthefollowingvalues FluidMassSource Liquid WaFluxLGMCF EnergySinkOptionenabledandsettoSpec MassFrac andTemp TemperaturetoSatTCartesianVelocityComponentstoGas Velocityu Gas Velocityv andGas Velocityw SubdomainLiqtoGas LiquidEnergySource Youwilldefinealiquidenergysourcetoaccountforthelatentheatduetophasechange Thelatentheatisassumedtocomefromtheliquid OntheFluidSourcestab withLiquidstillselected highlightEnergyandenablethetoggleSetthefollowingvalues Sourcetotheexpression Liquid WaFluxGL HtVapwa notetheminussign EnabletheSourceCoefficienttoggleandsetittotheexpression Liquid vf Liquid density Liquid Cp DtFalseMf notetheminussignprecedingLiquid vfinthisexpression ClickOKtocompletethedefinitionoftheSubdomain CreatinganInletBoundary GasInlet CreateaboundaryconditionnamedGasInletwherewetsteamentersOntheBasicSettingstab settheTypetoInletandthelocationtogasinletOntheBoundaryDetailsform settheMassandMomentumOptiontoNormalSpeedandsetavalueof341 m s SettheTurbulenceOptiontoLowSettheHeatTransferoptionstoStaticTemperatureandinputavalueof373 K OntheFluidValuestab highlightGasand SettheGasVolumeFractiontotheexpression1 0 45 0 4 1000SettheSteam3v mfmassfractionto1OntheFluidValuestab highlightLiquidandsettheLiquidVolumeFractiontotheexpression0 45 0 4 1000 ClickOKtodefinetheinletboundary CreatinganOpeningBoundary Opening CreateaboundaryconditionnamedOpeningwhichwillbeappliedattheouteredgeswheredryairmaybeentrainedintotheflowOntheBasicSettingstab settheTypetoOpeningandthelocationtoairinlet outeredge andoutletOntheBoundaryDetailsform settheMassandMomentumOptiontoOpeningPres andDirn SettheRelativePressureto0 Pa andtheDirectionOptiontoNormaltoBoundaryConditionSettheTurbulenceOptiontoMediumSettheHeatTransferoptionstoOpeningTemperatureandinputavalueof25 C OntheFluidValuestab highlightGasandsettheGasVolumeFractionto1andtheSteam3v mfmassfractionto0OntheFluidValuestab highlightLiquidandsettheLiquidVolumeFractionto0ClickOKtodefinetheopeningboundary SymmetryPlane Createaboundaryconditionnamedsym1 OntheBasicSettingstab settheTypetoSymmetryandthelocationtothelowthetafaceofthedomain oneside ClickOKtocompletetheboundarydefinition SymmetryPlane Createaboundaryconditionnamedsym2 OntheBasicSettingstab settheTypetoSymmetryandthelocationtothehighthetafaceofthedomain otherside ClickOKtocompletetheboundarydefinition CreatingaTimeStepExpression Inthiscase thevelocityatthegasinletisveryhighandtheinitialtimestepshouldbesmall Thelowervelocitiesattheoutletandopeningboundariesallowthetimesteptobeincreasedafterthegasinletpropertieshaveconverged Onceallthevaluesattheinlet outlet andopeningshaveconverged alargertimestepisusedtoallowtheoverallsolutiontosettle Inordertoaccountforallthesetimestepchanges anexpressionwillbecreated Double clickExpressionsintheOutlinetreeviewviewtheexpressiondefinedforDtstepwhichimplementstheabovelogic step 20 5 aitern 1 0e 5 s step aitern 20 5 step 100 5 aitern 1 0e 4 s step aitern 100 5 step 300 5 aitern 2 0e 4 s step aitern 300 5 step 500 5 aitern 5 0e 4 s step aitern 500 5 1 0e 3 s SolverControl Double clickontheSolverControlentryintheOutlinetoedititOntheBasicSettingstab SettheMaximumIterationsto1500SettheTimescaleControltoPhysicalTimescale ClickontheExpressioniconandenterth