fluent中多孔介质设置问题和算例Word文档格式.docx

fluent中多孔介质设置问题和算例Word文档格式.docx

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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，如此定义矢量为负〕

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一样。

总结一下，与君共享!

Tutorial7.ModelingFlowThroughPorousMedia

Introduction

Manyindustrialapplicationsinvolvethemodelingofflowthroughporousmedia,suchasfilters,catalystbeds,andpacking.Thistutorialillustrateshowtosetupandsolveaprobleminvolvinggasflowthroughporousmedia.

Theindustrialproblemsolvedhereinvolvesgasflowthroughacatalyticconverter.Catalyticconvertersaremonlyusedtopurifyemissionsfromgasolineanddieselenginesbyconvertingenvironmentallyhazardousexhaustemissionstoacceptablesubstances.

Examplesofsuchemissionsincludecarbonmonoxide（CO）,nitrogenoxides（NOx）,andunburnedhydrocarbonfuels.Theseexhaustgasemissionsareforcedthroughasubstrate,whichisaceramicstructurecoatedwithametalcatalystsuchasplatinumorpalladium.

Thenatureoftheexhaustgasflowisaveryimportantfactorindeterminingtheperformanceofthecatalyticconverter.Ofparticularimportanceisthepressuregradientandvelocitydistributionthroughthesubstrate.HenceCFDanalysisisusedtodesignefficientcatalyticconverters:

bymodelingtheexhaustgasflow,thepressuredropandtheuniformityofflowthroughthesubstratecanbedetermined.Inthistutorial,FLUENTisusedtomodeltheflowofnitrogengasthroughacatalyticconvertergeometry,sothattheflowfieldstructuremaybeanalyzed.

Thistutorialdemonstrateshowtodothefollowing:

_Setupaporouszoneforthesubstratewithappropriateresistances.

_Calculateasolutionforgasflowthroughthecatalyticconverterusingthepressurebasedsolver.

_Plotpressureandvelocitydistributiononspecifiedplanesofthegeometry.

_Determinethepressuredropthroughthesubstrateandthedegreeofnon-uniformityofflowthroughcrosssectionsofthegeometryusingX-Yplotsandnumericalreports.

ProblemDescription

ThecatalyticconvertermodeledhereisshowninFigure7.1.Thenitrogenflowsinthroughtheinletwithauniformvelocityof22.6m/s,passesthroughaceramicmonolithsubstratewithsquareshapedchannels,andthenexitsthroughtheoutlet.

Whiletheflowintheinletandoutletsectionsisturbulent,theflowthroughthesubstrateislaminarandischaracterizedbyinertialandviscouslosscoefficientsintheflow（X）direction.Thesubstrateisimpermeableinotherdirections,whichismodeledusinglosscoefficientswhosevaluesarethreeordersofmagnitudehigherthanintheXdirection.

SetupandSolution

Step1:

Grid

1.Readthemeshfile（catalyticconverter.msh）.

File/Read/Case...

2.Checkthegrid.Grid/Check

FLUENTwillperformvariouschecksonthemeshandreporttheprogressintheconsole.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:

Models

1.Retainthedefaultsolversettings.Define/Models/Solver...

2.Selectthestandardk-εturbulencemodel.Define/Models/Viscous...

Step3:

Materials

1.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.Settheboundaryconditions