FLOW-3D多孔介质模型-渗流模型.ppt

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1、第四章、FLOW-3D多孔介质模型FLOW-3D®v9.4ExamplesofPorousMedia10/6/2021UserTrainingSpongeWireScreenStreambedSinterMetalFilterPaperTubeBundlePorouscomponentsRequire2computationalcellstoadequatelyresolveModelobjectascomponentifSignificantgradientsoccurthroughthicknessofmaterialMaterialisanisotropicPorous

2、materialmaybeIsotropic(e.g.bedofuniformparticles)Anisotropic(e.g.tubebundles)PorousbafflesNothickness,resideoncellfacesBestformodelingscreensDragcanbelinearorquadraticModelassumesbaffleissaturated,nobubblepressureacrossTypesofPorousObjectsinFLOW-3D10/6/2021UserTrainingPorousMediaModelingThe

3、oryListoftopics介绍达西定律（Darcylaw）介绍FLOW-3D®拖曳力模型(dragmodel)介绍饱和多孔介质模型(thesaturatedporousmediamodel)介绍拖曳力系数与渗透率的关系(dragcoefficientandpermeability)如何处理流体在多孔介质中的各向异性(anisotropy)特征介绍非饱和多孔介质模型(theunsaturatedporousmediamodel)达西定律（DarcyLaw）Q:unitsofvolumepertime(e.g.,m³/s)A:cross-sectionalarea(Pb−Pa

4、):thepressuredropμ:dynamicviscosityΚ:thepermeabilityofthemedium(unitsofarea,e.g.m²)L:thelengthDarcy’sLaw:Flowratethroughporousmediaisproportionaltopressuredropaccordingto:wherev=macroscopic(superficial)velocity(FLOW-3Dcomputesandreportsmicroscopicvelocity)K=intrinsicpermeability-maybeisotro

5、picoranisotropic(directional)m=dynamicviscosityP=fluidpressurePermeabilityPropertyoftheporousmaterialRepresentstheaverageresistancetoflowinacontrolvolumeDarcy’slawrepresentsviscouslossesthroughporesApplicablewhenporeReynoldsnumberRep~1,whereRep=ApplieswelltotightlypackedspheresandfibersDoes

6、notrepresentinertiallossesinlooselypackedbedsViscousDraginPorousMedia:Darcy’sLawInertialdragbecomessignificantwhenRepexceeds10Darcy’sLawcanbeextendedtoincludeinertialeffectsQuadraticdrag:Forchheimer’sEquationInertialLosses:Forchheimer’sEquationviscoustransitionalinertialwherer=fluiddensityU

7、nderstandingFLOW-3D®’sDragModel由于流体在多孔介质中受到的很多阻力太小而无法求解，所以用一个均布的阻力系数来计算：K表示拖曳力系数，也就是流体在多孔介质中的流动阻力。TotalaccelerationInertiaAcc.duetopress.gradientAccel.duetoviscosityAccel.duetogravityDrageffectsVf=Volumefraction(porosity)ofcomputationalcellAf=Diagonalte