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7.19.6UserInputsforPorousMediaWhenyouaremodelingaporousregion,theonlyadditionalinputsfortheproblemsetupareasfollows.Optionalinputsareindicatedassuch.1.Definetheporouszone.2.Definetheporousvelocityformulation.(optional)3.Identifythefluidmaterialflowingthroughtheporousmedium.4.Enablereactionsfortheporouszone,ifappropriate,andselectthereactionmechanism.5.EnabletheRelativeVelocityResistanceFormulation.Bydefault,thisoptionisalreadyenabledandtakesthemovingporousmediaintoconsideration(asdescribedinSection7.19.6).6.Settheviscousresistancecoefficients(inEquation7.19-1,orinEquation7.19-2)andtheinertialresistancecoefficients(inEquation7.19-1,orinEquation7.19-2),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,youwillenterthecoefficientsandinEquation7.19-3insteadoftheresistancecoefficientsandflowdirection.YouwillsetallparametersfortheporousmediumintheFluidpanel(Figure7.19.1),whichisopenedfromtheBoundaryConditionspanel(asdescribedinSection7.1.4).Figure7.19.1:TheFluidPanelforaPorousZoneDefiningthePorousZoneAsmentionedinSection7.1,aporouszoneismodeledasaspecialtypeoffluidzone.Toindicatethatthefluidzoneisaporousregion,enablethePorousZoneoptionintheFluidpanel.Thepanelwillexpandtoshowtheporousmediainputs(asshowninFigure7.19.1).DefiningthePorousVelocityFormulationTheSolverpanelcontainsaPorousFormulationregionwhereyoucaninstructFLUENTtouseeitherasuperficialorphysicalvelocityintheporousmediumsimulation.Bydefault,thevelocityissettoSuperficialVelocity.FordetailsaboutusingthePhysicalVelocityformulation,seeSection7.19.7.DefiningtheFluidPassingThroughthePorousMediumTodefinethefluidthatpassesthroughtheporousmedium,selecttheappropriatefluidintheMaterialNamedrop-downlistintheFluidpanel.Ifyouwanttocheckormodifythepropertiesoftheselectedmaterial,youcanclickEdit...toopentheMaterialpanel;thispanelcontainsjustthepropertiesoftheselectedmaterial,notthefullcontentsofthestandardMaterialspanel.Ifyouaremodelingspeciestransportormultiphaseflow,theMaterialNamelistwillnotappearintheFluidpanel.Forspeciescalculations,themixturematerialforallfluid/porouszoneswillbethematerialyouspecifiedintheSpeciesModelpanel.Formultiphaseflows,thematerialsarespecifiedwhenyoudefinethephases,asdescribedinSection23.10.3.EnablingReactionsinaPorousZoneIfyouaremodelingspeciestransportwithreactions,youcanenablereactionsinaporouszonebyturningontheReactionoptionintheFluidpanelandselectingamechanismintheReactionMechanismdrop-downlist.Ifyourmechanismcontainswallsurfacereactions,youwillalsoneedtospecifyavaluefortheSurface-to-VolumeRatio.Thisvalueisthesurfaceareaoftheporewallsperunitvolume(),andcanbethoughtofasameasureofcatalystloading.Withthisvalue,FLUENTcancalculatethetotalsurfaceareaonwhichthereactiontakesplaceineachcellbymultiplyingbythevolumeofthecell.SeeSection14.1.4fordetailsaboutdefiningreactionmechanisms.SeeSection14.2fordetailsaboutwallsurfacereactions.IncludingtheRelativeVelocityResistanceFormulationPriortoFLUENT6.3,caseswithmovingreferenceframesusedtheabsolutevelocitiesinthesourcecalculationsforinertialandviscousresistance.Thisapproachhasbeenenhancedsothatrelativevelocitiesareusedfortheporoussourcecalculations(Section7.19.2).UsingtheRelativeVelocityResistanceFormulationoption(turnedonbydefault)allowsyoutobetterpredictthesourcetermsforcasesinvolvingmovingmeshesormovingreferenceframes(MRF).Thisoptionworkswellincaseswithnon-movingandmovingporousmedia.NotethatFLUENTwillusetheappropriatevelocities(relativeorabsolute),dependingonyourcasesetup.DefiningtheViscousandInertialResistanceCoefficientsTheviscousandinertialresistancecoefficientsarebothdefinedinthesamemanner.ThebasicapproachfordefiningthecoefficientsusingaCartesiancoordinatesystemistodefineonedirectionvectorin2Dortwodirectionvectorsin3D,andthenspecifytheviscousand/orinertialresistancecoefficientsineachdirection.In2D,theseconddirection,whichisnotexplicitlydefined,isnormaltotheplanedefinedbythespecifieddirectionvectorandthedirectionvector.In3D,thethirddirectionisnormaltotheplanedefinedbythetwospecifieddirectionvectors.Fora3Dproblem,theseconddirectionmustbenormaltothefirst.Ifyoufailtospecifytwonormaldirections,thesolverwillensurethattheyarenormalbyignoringanycomponentoftheseconddirectionthatisinthefirstdirection.Youshouldthereforebecertainthatthefirstdirectioniscorrectlyspecified.Youca