fluent中多孔介质模型的设置.docx
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7.19.6UserInputsforPorousMedia
Whenyouaremodelingaporousregion,theonlyadditionalinputsfortheproblemsetupareasfollows.Optionalinputsareindicatedassuch.
1. Definetheporouszone.
2. Definetheporousvelocityformulation.(optional)
3. Identifythefluidmaterialflowingthroughtheporousmedium.
4. Enablereactionsfortheporouszone,ifappropriate,andselectthereactionmechanism.
5. Enablethe RelativeVelocityResistanceFormulation.Bydefault,thisoptionisalreadyenabledandtakesthemovingporousmediaintoconsideration(asdescribedinSection 7.19.6).
6. Settheviscousresistancecoefficients( inEquation 7.19-1,or inEquation 7.19-2)andtheinertialresistancecoefficients( inEquation 7.19-1,or inEquation 7.19-2),anddefinethedirectionvectorsforwhichtheyapply.Alternatively,specifythecoefficientsforthepower-lawmodel.
7. Specifytheporosityoftheporousmedium.
8. Selectthematerialcontainedintheporousmedium(requiredonlyformodelsthatincludeheattransfer).Notethatthespecificheatcapacity, ,fortheselectedmaterialintheporouszonecanonlybeenteredasaconstantvalue.
9. Setthevolumetricheatgenerationrateinthesolidportionoftheporousmedium(oranyothersources,suchasmassormomentum).(optional)
10. Setanyfixedvaluesforsolutionvariablesinthefluidregion(optional).
11. Suppresstheturbulentviscosityintheporousregion,ifappropriate.
12. Specifytherotationaxisand/orzonemotion,ifrelevant.
Methodsfordeterminingtheresistancecoefficientsand/orpermeabilityarepresentedbelow.Ifyouchoosetousethepower-lawapproximationoftheporous-mediamomentumsourceterm,youwillenterthecoefficients and inEquation 7.19-3 insteadoftheresistancecoefficientsandflowdirection.
Youwillsetallparametersfortheporousmediuminthe Fluid panel (Figure 7.19.1),whichisopenedfromthe BoundaryConditions panel (asdescribedinSection 7.1.4).
Figure7.19.1:
The Fluid PanelforaPorousZone
DefiningthePorousZone
AsmentionedinSection 7.1,aporouszoneismodeledasaspecialtypeoffluidzone.Toindicatethatthefluidzoneisaporousregion,enablethe PorousZoneoptioninthe Fluid panel.Thepanelwillexpandtoshowtheporousmediainputs(asshowninFigure 7.19.1).
DefiningthePorousVelocityFormulation
The Solver panelcontainsa PorousFormulation regionwhereyoucaninstruct FLUENT touseeitherasuperficialorphysicalvelocityintheporousmediumsimulation.Bydefault,thevelocityissetto SuperficialVelocity.Fordetailsaboutusingthe PhysicalVelocity formulation,seeSection 7.19.7.
DefiningtheFluidPassingThroughthePorousMedium
Todefinethefluidthatpassesthroughtheporousmedium,selecttheappropriatefluidinthe MaterialName drop-downlistinthe Fluid panel.Ifyouwanttocheckormodifythepropertiesoftheselectedmaterial,youcanclick Edit... toopenthe Material panel;thispanelcontainsjustthepropertiesoftheselectedmaterial,notthefullcontentsofthestandard Materials panel.
Ifyouaremodelingspeciestransportormultiphaseflow,the MaterialName listwillnotappearinthe Fluid panel.Forspeciescalculations,themixturematerialforallfluid/porouszoneswillbethematerialyouspecifiedinthe SpeciesModel panel.Formultiphaseflows,thematerialsarespecifiedwhenyoudefinethephases,asdescribedinSection 23.10.3.
EnablingReactionsinaPorousZone
Ifyouaremodelingspeciestransportwithreactions,youcanenablereactionsinaporouszonebyturningonthe Reaction optioninthe Fluid panelandselectingamechanisminthe ReactionMechanism drop-downlist.
Ifyourmechanismcontainswallsurfacereactions,youwillalsoneedtospecifyavalueforthe Surface-to-VolumeRatio.Thisvalueisthesurfaceareaoftheporewallsperunitvolume( ),andcanbethoughtofasameasureofcatalystloading.Withthisvalue, FLUENT cancalculatethetotalsurfaceareaonwhichthereactiontakesplaceineachcellbymultiplying bythevolumeofthecell.SeeSection 14.1.4 fordetailsaboutdefiningreactionmechanisms.SeeSection 14.2fordetailsaboutwallsurfacereactions.
IncludingtheRelativeVelocityResistanceFormulation
Priorto FLUENT 6.3,caseswithmovingreferenceframesusedtheabsolutevelocitiesinthesourcecalculationsforinertialandviscousresistance.Thisapproachhasbeenenhancedsothatrelativevelocitiesareusedfortheporoussourcecalculations(Section 7.19.2).Usingthe RelativeVelocityResistanceFormulationoption(turnedonbydefault)allowsyoutobetterpredictthesourcetermsforcasesinvolvingmovingmeshesormovingreferenceframes(MRF).Thisoptionworkswellincaseswithnon-movingandmovingporousmedia.Notethat FLUENT w