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经过痛苦的一段经历，终于将局部问题真相大白，为了使保位同仁不再经过我之痛苦，现在将本人多孔介质经验公布如下，希望各位能加精：1。Gambit中划分网格之后，定义需要做为多孔介质的区域为fluid,与缺省的fluid分别开来，再定义其名称，我习惯将名称定义为porous;2。在fluent中定义边界条件define-boundarycondition-porous(刚定义的名称)，将其设置边界条件为fluid,点击set按钮即弹出与fluid边界条件一样的对话框，选中porouszone与laminar复选框,再点击porouszone标签即出现一个带有滚动条的界面；3。porouszone设置方法：1）定义矢量：二维定义一个矢量，第二个矢量方向不用定义，是与第一个矢量方向正交的；三维定义二个矢量，第三个矢量方向不用定义，是与第一、二个矢量方向正交的；（如何知道矢量的方向：打开grid图，看看X,Y,Z的方向，如果是X向，矢量为1,0,0,同理Y向为0,1,0，Z向为0,0,1,如果所需要的方向与坐标轴正向相反，则定义矢量为负）圆锥坐标与球坐标请参考fluent帮助。2）定义粘性阻力1/a与内部阻力C2：请参看本人上一篇博文“终于搞清fluent中多孔粘性阻力与内部阻力的计算方法”，此处不赘述；3）如果了定义粘性阻力1/a与内部阻力C2,就不用定义C1与C0，因为这是两种不同的定义方法，C1与C0只在幂率模型中出现，该处保持默认就行了；4）定义孔隙率porousity，默认值1表示全开放，此值按实验测值填写即可。完了，其他设置与普通k-e或RSM相同。总结一下，与君共享!Tutorial7.ModelingFlowThroughPorousMediaIntroductionManyindustrialapplicationsinvolvethemodelingofflowthroughporousmedia,suchasfilters,catalystbeds,andpacking.Thistutorialillustrateshowtosetupandsolveaprobleminvolvinggasflowthroughporousmedia.Theindustrialproblemsolvedhereinvolvesgasflowthroughacatalyticconverter.Catalyticconvertersarecommonlyusedtopurifyemissionsfromgasolineanddieselenginesbyconvertingenvironmentallyhazardousexhaustemissionstoacceptablesubstances.Examplesofsuchemissionsincludecarbonmonoxide(CO),nitrogenoxides(NOx),andunburnedhydrocarbonfuels.Theseexhaustgasemissionsareforcedthroughasubstrate,whichisaceramicstructurecoatedwithametalcatalystsuchasplatinumorpalladium.Thenatureoftheexhaustgasflowisaveryimportantfactorindeterminingtheperformanceofthecatalyticconverter.Ofparticularimportanceisthepressuregradientandvelocitydistributionthroughthesubstrate.HenceCFDanalysisisusedtodesignefficientcatalyticconverters:bymodelingtheexhaustgasflow,thepressuredropandtheuniformityofflowthroughthesubstratecanbedetermined.Inthistutorial,FLUENTisusedtomodeltheflowofnitrogengasthroughacatalyticconvertergeometry,sothattheflowfieldstructuremaybeanalyzed.Thistutorialdemonstrateshowtodothefollowing:_Setupaporouszoneforthesubstratewithappropriateresistances._Calculateasolutionforgasflowthroughthecatalyticconverterusingthepressurebasedsolver._Plotpressureandvelocitydistributiononspecifiedplanesofthegeometry._Determinethepressuredropthroughthesubstrateandthedegreeofnon-uniformityofflowthroughcrosssectionsofthegeometryusingX-Yplotsandnumericalreports.ProblemDescriptionThecatalyticconvertermodeledhereisshowninFigure7.1.Thenitrogenflowsinthroughtheinletwithauniformvelocityof22.6m/s,passesthroughaceramicmonolithsubstratewithsquareshapedchannels,andthenexitsthroughtheoutlet.Whiletheflowintheinletandoutletsectionsisturbulent,theflowthroughthesubstrateislaminarandischaracterizedbyinertialandviscouslosscoefficientsintheflow(X)direction.Thesubstrateisimpermeableinotherdirections,whichismodeledusinglosscoefficientswhosevaluesarethreeordersofmagnitudehigherthanintheXdirection.SetupandSolutionStep1:Grid1.Readthemeshfile(catalyticconverter.msh).File/Read/Case...2.Checkthegrid.Grid/CheckFLUENTwillperformvariouschecksonthemeshandreporttheprogressintheconsole.Makesurethattheminimumvolumereportedisapositivenumber.3.Scalethegrid.Grid!Scale...(a)SelectmmfromtheGridWasCreatedIndrop-downlist.(b)ClicktheChangeLengthUnitsbutton.Alldimensionswillnowbeshowninmillimeters.(c)ClickScaleandclosetheScaleGridpanel.4.Displaythemesh.Display/Grid...(a)Makesurethatinlet,outlet,substrate-wall,andwallareselectedintheSurfacesselectionlist.(b)ClickDisplay.(c)RotatetheviewandzoomintogetthedisplayshowninFigure7.2.(d)ClosetheGridDisplaypanel.Thehexmeshonthegeometrycontainsatotalof34,580cells.Step2:Models1.Retainthedefaultsolversettings.Define/Models/Solver...2.Selectthestandardk-εturbulencemodel.Define/Models/Viscous...Step3:Materials1.AddnitrogentothelistoffluidmaterialsbycopyingitfromtheFluentDatabaseformaterials.Define/Materials...(a)ClicktheFluentDatabase...buttontoopentheFluentDatabaseMaterialspanel.i.Selectnitrogen(n2)fromthelistofFluentFluidMaterials.ii.ClickCopytocopytheinformationfornitrogentoyourlistoffluidmaterials.iii.ClosetheFluentDatabaseMaterialspanel.(b)ClosetheMaterialspanel.Step4:BoundaryConditions.Define/BoundaryConditions...1.Settheboundaryconditionsforthefluid(fluid).(a)SelectnitrogenfromtheMaterialNamedrop-downlist.(b)ClickOKtoclosetheFluidpanel.2.Settheboundaryconditionsforthesubstrate(substrate).(a)SelectnitrogenfromtheMaterialNamedrop-downlist.(b)EnablethePorousZoneoptiontoactivatetheporouszonemodel.(c)EnabletheLaminarZoneoptiontosolvetheflowintheporouszonewithoutturbulence.(d)ClickthePorousZonetab.i.MakesurethattheprincipaldirectionvectorsaresetasshowninTable7.1.Usethescrollbartoaccessthefieldsthatarenotinitiallyvisibleinthepanel.ii.EnterthevaluesinTable7.2fortheViscousResistanceandInertialResistance.Scrolldowntoaccessthefieldsthatarenotinitiallyvisibleinthepanel.(e)ClickOKtoclosetheFluidpanel.3.Setthevelocityandturbulenceboundaryconditionsattheinlet(inlet).(a)Enter22.6m/sfortheVelocityMagnitude.(b)SelectIntensityandHydraulicDiameterfromtheSpecificationMethoddropdownlistintheTurbulencegroupbox.(c)Retainthedefaultvalueof10%fortheTurbulentIntensity.(d)