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MOFAT是一个有限元程序，模拟多相（水、油和气）流动和五种非惰性化学物质的运输。MOFAT模拟三种流体相系统中轻质或致密有机液体的流动。MOFAT将动态或被动气体模拟为完整的三项流动问题。可通过在变饱和的多孔介质中仅模拟水流，油水流或水-油-气流。MOFAT通过仅针对压力和饱和度超过规定公差的相位求解流动方向，实现了高度的计算效率。因此，如果NAPL不存在或存在残余饱和度，则MOFAT将局部消除那些流动方程。
MOFAT分析水中的对流 - 分散运输，NAPL，通过假定流体相和固相之间的局部平衡或非平衡分配来确定气相。MOFAT考虑了相间质量传递和相密度的成分依赖性。使用了对土壤毛细按压力关系的简明但准确的描述，其确保了单相、两相和三相条件之间的自然连续性。用户可以使用估算土壤性SOILPARA。MOFAT for Windows包括一个图形预处理器，网络编辑器和带有在线帮助的后处理器。
考虑由于流体截留导致的油渗透性的滞后现象
仅对水流，耦合的油水流或水-油气流进行建模
【英文介绍】
MOFATisafiniteelementprogramthatsimulatesmultiphase(water,oilandgas)flowandtransportofuptofivenon-inertchemicalspecies.MOFATmodelsflowoflightordenseorganicliquidsinthreefluidphasesystems.MOFATsimulatesdynamicorpassivegasasafullthree-phaseflowproblem.Modelwaterflowonly,oil-waterflow,orwater-oil-gasflowinvariably-saturatedporousmedia.MOFATachievesahighdegreeofcomputationalefficiencybysolvingflowequationsonlyforphasesthatareundergoingchangesinpressuresandsaturationsabovespecifiedtolerances.Therefore,ifNAPLisabsentorexistsataresidualsaturation,MOFATwilllocallyeliminatethoseflowequations.MOFATanalyzesconvective-dispersivetransportinwater,NAPL,andgasphasesbyassuminglocalequilibriumornonequilibriumpartitioningamongthefluidandsolidphases.MOFATconsidersinterphasemasstransferandcompositionaldependenceofphasedensities.Aconcisebutaccuratedescriptionofsoilcapillarypressurerelationsisusedwhichassuresnaturalcontinuitybetweensingle-phase,two-phaseandthree-phaseconditions.TheusercanestimatesoilpropertiesusingSOILPARA.MOFATforWindowsincludesagraphicalpreprocessor,mesheditorandpostprocessorwithon-linehelp.
MOFATforWindowsincludesagraphicalpre-processor,MeshEditorandpost-processorwithon-linehelp.
Simulatemultiphase(water,oilandgas)flowandtransportofuptofivenon-inertchemicalspeciesinMOFAT.Modelflowoflightordenseorganicliquidsinthreefluidphasesystems.Simulatedynamicorpassivegasasafullthree-phaseflowproblem.Modelwaterflowonly,oil-waterflow,orwater-oil-gasflowinvariably-saturatedporousmedia.MOFATachievesahighdegreeofcomputationalefficiencybysolvingflowequationsateachnode(onthefinite-elementmesh)onlyforphasesthatareundergoingchangesinpressuresandsaturationsabovespecifiedtolerancesusinganewadaptivesolutiondomainmethod.Therefore,ifNAPLisabsentorexistsataresidualsaturation,MOFATwilllocallyeliminatethoseflowequations.MOFATanalyzesconvective-dispersivetransportinwater,NAPL,andgasphasesbyassuminglocalequilibriumornonequilibriumpartitioningamongthefluidandsolidphases.MOFATconsidersinterphasemasstransferandcompositionaldependenceofphasedensities.Aconcisebutaccuratedescriptionofsoilcapillarypressurerelationsisusedwhichassuresnaturalcontinuitybetweensingle-phase,two-phaseandthree-phaseconditions.TheusercanestimatesoilpropertiesusingSOILPARA.
MOFATFEATURES
-Simulatemultiphasetransportofuptofivenon-inertchemicalspecies.
-Modelflowoflightordenseorganicliquidsinthreefluidphasesystems.
-SolveflowequationsforphasesexhibitingtransientbehaviorusingtheASDmethod.
-Simulatedynamicorpassivegasasafullthree-phaseflowproblem.
-Useathree-phasevanGenuchtenmodelforsaturation-pressure-permeabilityrelations.
-Handlefluxtype,specifiedhead,specifiedconcentrationormixedtypeboundaryconditions.
-Considerhysteresisinoilpermeabilityduetofluidentrapment.
-Modelwaterflowonly,coupledoil-waterflow,orwater-oil-gasflow.
MOFATTECHNICALINFORMATION
ThissectionisextractedfromtheEPADocumentEPA/600/2-91/020May1991:
MOFAT:ATWO-DIMENSIONALFINITEELEMENTPROGRAMFORMULTIPHASEFLOWANDMULTICOMPONENTTRANSPORT
ABSTRACT
Thisreportdescribesatwo-dimensionalfiniteelement-modelforcoupledmultiphaseflowandmulticomponenttransportinplanarorradially-symmetricverticalsections.Flowandtransportofthreefluidphases-water,nonaqueousphaseliquid(NAPL)andgas-isconsideredbytheprogramwhichalsohandlescasesinwhichgasand/orNAPLphasesareabsentinpartorallofthedomainatanygiventime.Theprogramwillsimulateflowonlyorcoupledflowandtransport.Theflowmodulecanbeusedtoanalyzetwo-phaseflowofwaterandNAPLinasystemwithgaspresentbutatconstantpressureorexplicitthree-phaseflowofwater,NAPLandgasatvariablepressure.Thetransportmodulecanhandleuptofivecomponentswhichpartitionamongwater,NAPL,gasandsolidphasesassumingeitherlocalequilibriuminterphasemasstransferorfirst-orderkineticallycontrolledmasstransfer.Thegoverningequationsaresolvedusinganefficientupstream-weightedfiniteelementscheme.Requiredinputforflowanalysesconsistsofinitialconditions,soilhydraulicproperties,fluidproperties,timeintegrationparameters,boundaryconditiondataandmeshgeometry.Three-phasepermeability-saturation-capillarypressurerelationsaredefinedbyanextensionofthevanGenuchtenmodelwhichconsiderseffectsofoilentrapmentduringperiodsofwaterimbibition.Fortransportanalyses,additionalinputdataareporousmediadispersivities,initialwaterphaseconcentrations,equilibriumpartitioncoefficients,componentdensities,diffusioncoefficients,first-orderdecaycoefficients,masstransfercoefficients(fornonequilibriumanalyses)andboundaryconditiondata.Time-dependentboundaryconditionsfortheflowanalysismayinvolveuser-specifiedphaseheadsatnodesorphasefluxesalongaboundarysegmentwithzerofluxasthedefaultcondition.Fortransportanalyses,initialconditionsarespecifiedintermsofequilibriumwaterphaseconcentrationsofeachpartitionablecomponent.Time-dependentboundaryconditionsmaybestipulatedasequilibriumwaterphaseconcentrationsintheporousmediumasprescribedfluxesdefinedintermsofaspecifiedconcentrationintheinfluentliquidorwithzerodispersivefluxspecified.Programoutputconsistsofbasicinformationoninputparameters,meshdetailsandinitialconditionspluspressureheads,saturationsandvelocitiesforeachphaseateverynodeforspecifiedoutputintervals.Fortransportanalyses,thephaseconcentrationsateachnodeareoutputateachprintoutinterval.
MOFATWINDOWSINTERFACE
WhatistheMOFATPre-processor?
TheMOFATpre-processorwasdesignedtowritedatafilesandstoredataforMOFATnumericalmodelruns.Thepre-processorworksinconcertwiththeMeshEditorandwiththepost-processortomakeacompletegraphicalinterfacetotheUSEPA'sMultiphaseOrganicFlowandTransportsimulator.TherearefourdistinctprogramsinMOFAT:theMOFATnumericalmodel,theMOFATPre-processor,theMeshEditor,andthePost-processor.Eachrelyononeanotherfordatainputandoutput.Forinstance,theMeshEditorisadumbprogramthatdoesn'tcarewhetheritisworkingwithMOFAT,orwithBIOF&T,MOVERorMARS.Itsimplyreadsinatemplatefilethatletsitknowwhatassociations(forexample,soiltypes,boundaryconditions,etc.)arelegalforMOFATandwhatassociationshavebeenenteredinthepre-processorforthatmeshfile.ThisarrangementallowsfordevelopmentoftheMeshEditortoincludemorefeaturesinthefuturewithoutdisturbingthemainMOFATprogram.
TheMOFATPre-processorallowsforentryofControlParameters(forexample,whetherornottransportwillbesolvedforintherun),InitialConditions(initialheadsofwaterandoil),SpeciesPropertiesforuptofivespecies,FluidProperties,TransportProperties,BoundaryConditions,andMaterialPropertiesforuptotensoils.Manyvaluesenteredinthepre-processorareusedintheMeshEditor.Valueslikenon-uniformwaterheadsaredefinedinthepre-processor,thenlaterassignedtonodesintheMeshEditor.MaterialProperties,BoundaryConditions,non-uniformoilheads,andindividualnodeprintoutsareallassignedtonodesoredgesintheMeshEditor.
TheMOFATPre-processoralsohasarunmoduleforwritinginputdatafilesandexecutingtheMOFATnumericalmodel.Itisimportanttounderstandthatthepre-processordoesnotreadMOFATnumericalmodeldatafiles,itonlywritesthem.Thepre-processorandMeshEditorusetextfilestosaveprojectdatatodiskandtoopenprojects.Afteradatafileforthenumericalmodelshasbeenwritten,youcanchangeindividualcontrolparametersbutthesechangeswillnotbereflectedinthepre-processor.
TheMOFATPre-processorInterface
AfterclickingontheMOFATpre-processorforthefirsttime,asetupnotebookwillappearonthescreen.ThisnotebookactsasabinderforallMOFATdatafiles,forlinkstotheMeshEditorandaprojectmesh,forwritinginputfilesandrunningthenumericalmodel,andforcuecardsandadditionalhelp.ThisnotebookisavailableatanytimebyselectingTools|SetupfromthemainmenuorTools|Runner.Topreventthisnotebookfromautomaticallydisplayingeverytimethepre-processorisrun,clickofftheShowAgaincheckboxontheCueCardspage.
Note:allvariablenameslikeITRNareincapitallettersandmatchexactlythenamesusedintheMOFATFORTRANsourcecode.
TheMOFATpre-processorrunsunderWindows3.X,Windows95andWindowsNT.CurrentlyallMOFATprogramsare16-bit,sothereisnospeedormultitaskingadvantagetorunningtheprogramsundera32-bitoperatingsystem.Formostproblems,thepre-processorwillrunwellunder4MBofRAM.Whendealingwithlargefiniteelementmeshes,youwillfindthatreadingandwritingfiles,andworkingwiththeMeshEditorwillgreatlyslowdownunder4MBofRAM.Also,thenumericalmodelwillnotrununder4MBofRAMforlargerproblems.
TheMOFATpre-processorusesacommonly-usedtabbednotebookinterfacetoallowquickeditingofinputfiles.Themainprogramhastwosetsoftabs,onealongthebottomwhichseparatesmajorsectionsoftheinterface,and,onsomeofthelargenotebookpages,tabsalongthetopthatseparatesubsectionstomakethemostuseofavailablescreenspace.Forexample,clickingonthebottomtab"BoundarySchedules"takesyoutotheboundaryschedulenotebook.Herethereisatabbednotebookforeditingtype1andtype2boundaryschedules.
