《多孔跳跃边界条》word版

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1、PorousJumpBoundaryConditionsPorousjumpconditionsareusedtomodelathin"membrane''thathasknownvelocity(pressure-drop)characteristics.Itisessentiallya1Dsimplificationoftheporousmediamodelavailableforcellzones.Examplesofusesfortheporousjumpconditionincludemodelingpressuredropsthroughscreensa

2、ndfilters,andmodelingradiatorswhenyouarenotconcernedwithheattransfer.Thissimplermodelshouldbeusedwheneverpossible(insteadofthefullporousmediamodel)becauseitismorerobustandyieldsbetterconvergence.ThethinporousmediumhasafinitethicknessoverwhichthepressurechangeisdefinedasacombinationofDa

3、rcy'sLawandanadditionalinertiallossterm:(7.22-1)where  isthelaminarfluidviscosity,  isthepermeabilityofthemedium,  isthepressure-jumpcoefficient,  isthevelocitynormaltotheporousface,and isthethicknessofthemedium.Appropriatevaluesfor  and  canbecalculatedusingthetechniquesdescribedinSec

4、tion  7.19.6.UserInputsforthePorousJumpModelOncetheporousjumpzonehasbeenidentified(inthe BoundaryConditions panel),youwillsetallmodelinginputsfortheporousjumpinthe PorousJump panel(Figure  7.22.1),whichisopenedfromthe BoundaryConditions panel (asdescribedinSection  7.1.4).Figure7.22.1:

5、 The PorousJump PanelTheinputsrequiredfortheporousjumpmodelareasfollows:1.  Identifytheporous-jumpzone.2.  Setthe FacePermeability ofthemedium(  inEquation  7.22-1).3.  Setthe PorousMediumThickness ( ).4.  Setthe Pressure-JumpCoefficient ( ).5.  Definethediscretephaseboundaryconditionf

6、ortheporousjump(fordiscretephasecalculations).IdentifyingthePorousJumpZoneSincetheporousjumpmodelisa1Dsimplificationoftheporousmediamodel,theporous-jumpzonemustbemodeledastheinterfacebetweencells,ratherthanacellzone.Thustheporous-jumpzoneisatypeofinternalfacezone(wherethefacesarelinese

7、gmentsin2Dortriangles/quadrilateralsin3D).Iftheporous-jumpzoneisnotidentifiedassuchbydefaultwhenyoureadinthegrid(i.e.,ifitisidentifiedasanothertypeofinternalfacezone),youcanusethe BoundaryConditions panel tochangetheappropriatefacezonetoa porous-jump zone.Define  BoundaryConditions..