简介：Duringthedevelopmentoflowpermeabilityreservoirs.theinteractionbetweenfluidflowandrock-massdeformationisobvious.Onthebasisoffluidmechanicsinporousmediaandelasto-plastictheory.theauthorpresentsanequivalentcontinuummodeltosimulatefluidflowinfracturedlow-permeabilityoilreservoircoupledwithgeo-stress.Themodelnotonlyreflectstheporositychangeofmatrix,butalsothepermeabilitychangeduetotheopeningandclosingoffracture.Byanalyzingofsimulationresults,thechangesinporosityandpermeabilityandtheireffectonoildevelopmentarestudied.

简介：Thispaperdescribesanovelsharpinterfaceapproachformodelingthecavitationphenomenainincompressibleviscousflows.Aone-fieldformulationisadoptedforthevapor-liquidtwo-phaseflowandtheinterfaceistrackedusingavolumeoffluid(VOF)method.PhasechangeattheinterfaceismodeledusingasimplificationoftheRayleigh-Plessetequation.Interfacejumpconditionsinvelocityandpressurefieldaretreatedusingalevelsetbasedghostfluidmethod.Thelevelsetfunctionisconstructedfromthevolumefractionfunction.Amarchingcubesmethodisusedtocomputetheinterfaceareaattheinterfacegridcells.Aparallelfastmarchingmethodisemployedtopropagateinterfaceinformationintothefield.Adescriptionoftheequationsandnumericalmethodsispresented.Resultsforacavitatinghydrofoilarecomparedwithexperimentaldata.

简介：ThesedimentationofcircularparticlesinaverticalchannelfilledwithOldroyd-BfluidwasstudiedbyanimprovedDistributedLagrangeMultiplier/fictitiousdomain(DLM)method.Thesedimentingbehaviorsoftwoparticlesarepresentedfirstly,whichshowsthat,whentheparticlesaredroppedinaviscoealsticfluid,thestableconfigurationistheonewheretheparticlesarealignedparalleltotheflowdirectionwhentheMachnumberMislessthan1andtheelasticitynumberEisgreaterthan1.ThisagreeswellwiththeknownexperimentalinRef.[1]andsimulationresultsinRef.[2].Oursimulationsalsoshowthat,asinNewtonianfluid,thesedimentationoftheparticleswillbeacceleratedduetotheinteractionbetweenparticlesinaviscoealsticfluid.

简介：InthisarticletheUDFscriptfileintheFluentsoftwarewasrewrittenasthe'connectingfile'fortheFluentandtheANSYS/ABAQUSinorderthatthejoinedfilecanbeusedtodoaero-elasticcomputations.InthiswaythefluidfieldiscomputedbysolvingtheNavier-Stokesequationsandthestructuremovementisintegratedbythedynamicsdirectly.Ananalysisofthecomputedresultsshowsthatthiscoupledmethoddesignedforsimulatingaero-elasticsystemsisworkableandcanbeusedfortheotherfluid-structureinteractionproblems.

简介：Anumericalstudywasconductedforthefullydevelopedlaminarflowinrotatingcurvedellipticalpipe.Duetotherotation,theCoriolisforcecanalsocontributetothesecondaryflow.Theinteractionofrotationandcurvaturecomplicatestheflowcharacteristics.Theboundary-fittedcoordinatewasadoptedtostudytheflowcharacteristicintherotatingsystems.Theeffectsofrotationontheflowtransitionwerestudiedindetail.Thegenerationandmergenceofvorticesinrotatingcurvedellipticalpipeswerealsocapturedforthefirsttime.Thesimulationresultsshowthattheflowforthecaseoflargeaspectratioofthecross-sectionismorelikelytobeunstablethanthatforsmallerone.

简介：TheproblemofacreepingflowofNewtonianfluidextrudedfromaplaneslitoracircularpipe.intheabsenceofgravity,issimulatedsuccessfullybyusingthecontinuous-pressure-elementmethod,thediscontinuous-pressure-elementmethod,theconsistantpenaltymethod,thereducedintegrationpenaltymethodandthemodifiedreducedintegrationpenaltymethodproposedbyOden.Throughcomparisonsbetweenthesemethods,itisconvincedthatthediscontinuous-pressureinterpolationschemesresultinmoreaccuratemassconservationand,consequently,morerapidconvergenceofthefree-surfaceiterationthanthecontinuousonedoes.Thereducedintegrationpenaltymethodcanfurtherreducethecostofcomputationwhileretainingsufficientaccuracyofthesolution.

简介：Fluidcharacteristicsofarotarywingheatmeterwithsingle-channelwerestudiedthroughthereticalanalysis,numericalsimulationandexperiments.Theobtainedresultsshowthatthenumberofvanescanobviouslyinfluencetheheatmeter,butthewatertemperatureseldominfluencethemeter,andtheoptimalnumberofvaneis6-8.

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简介：TheUSM-θmodelofpowerlawfluidfordensetwo-phaseturbulentflowwasdeveloped,whichcombinestheunifiedsecond-ordermomentmodelfortwo-phaseturbulencewiththeparticlekinetictheoryfortheinter-particlecollision.Thismodelwasusedtosimulatetheturbulentflowofpowerlawfluidsingle-phaseinpipe.ItisshownthattheUSM?θmodelhasbetterpredictionresultthanthekf?εf?kp?εp?θmodel.TheUSM?θmodelwasthenusedtosimulatethedensetwo-phaseturbulentupflowofpowerlawfluidwithparticles.Withtheincreaseoftheflowexponent,thevelocitiesofpowerlawfluidandparticlesincreasenearthepipecentre.Comparisonbetweenthetwo-phaseflowofpowerlawfluid-particleandofliquid-particleindicatesthattheaxialfluctuationvelocityoffluidphaseandparticlephaseinliquid-particletwo-phaseflowissmallerthanthatinthepowerlawfluidtwo-phaseflow,butthetwo-phasevelocitiesofpowerlawfluid-particleandliquid-particleareclosetoeachother.

简介：Thehydrodynamicdamperisadevicetodecreasethemotionofarmamentcarrierbyuseofthewaterresistance.Whenhydrodynamicdamperrushesintothewaterchannelwithhighvelocity,itisacomplicatedflowphenomenonwithfluid-structureinteraction,freesurfaceandmovinginterface.NumericalsimulationusingtheSmoothedParticleHydrodynamics(SPH)methodcoupledwiththeFiniteElement(FE)methodwassuccessfullyconductedtopredictthedynamiccharacteristicsofhydrodynamicdamper.Thewaterresistance,thepressureintheinterfaceandthestressofstructurewereinvestigated,andtherelationshipamongthepeakofwaterresistance,initialvelocityandactualdraughtwasalsodiscussed.Theempiricalformulawasputforwardtopredictthewaterresistance.Anditisfoundthattheresistancecoefficientiscommonlyintherangeof0.3≤C≤0.5,whentheinitialvelocityislargerthan50m/s.ItcanbeseenthattheSPHmethodcoupledwiththeFEmethodhasmanyobviousadvantagesoverothernumericalmethodsforthiscomplicatedflowproblemwithfluid-structureinteraction.

简介：Astochasticsimulationoffluidflowinporousmediausingacomplexvariableexpressionmethod(SFCM)ispresentedinthispaper.Hydraulicconductivityisconsideredasarandomvariableandisthenexpressedincomplexvariableform,therealpartofwhichisadeterministicvalueandtheimaginarypartisavariablevalue.ThestochasticseepageflowissimulatedwiththeSFCMandiscomparedwiththeresultscalculatedwiththeMonteCarlostochasticfiniteelementmethod.InusingtheMonteCarlomethodtosimulatethestochasticseepageflowfield,thehydraulicconductivityisassumedinthreedifferentprobabilitydistributionsusingrandomsamplingmethod.Theobtainedseepageflowfieldisexaminedthroughskewnessanalysis,andtheskeweddistributionprobabilitydensityfunctionisgiven.TheheadmodevalueandtheheadcomprehensivestandarddeviationareusedtorepresentthestatisticsofcalculationresultsobtainedbytheMonteCarlomethod.ThestochasticseepageflowfieldsimulatedbytheSFCMisconfirmedtobesimilartothatgivenbytheMonteCarlomethodfromnumericalaspects.TherangeofcoefficientofvariationofhydraulicconductivityinSFCMislargerthanusedpreviouslyinstochasticseepageflowfieldsimulations,andthecomputationtimeisshort.TheresultsprovedthattheSFCMisaconvenientcalculatingmethodforsolvingthecomplexproblems.

简介：Themasstransportvelocityinathinlayerofmuddyfluidisstudiedtheoretically.Themudmotionisdrivenbyaperiodicpressureloadonthefreesurface,andthemudisdescribedbyapower-lawmodel.Basedonthekeyassumptionsoftheshallownessandthesmalldeformation,aperturbationanalysisisconducteduptothesecondordertofindthemeanEulerianvelocityinanEuleriancoordinatesystem.Thenumericaliterationmethodisadoptedtosolvethesenon-linearequationsoftheleadingorder.Fromthenumericalresults,boththefirst-orderflowfieldsandthesecond-ordermasstransportvelocitiesareexamined.Theverificationsaremadebycomparingthenumericalresultswithexperimentalresultsintheliterature,andagoodagreementisconfirmed.

简介：Thispapermakesthethermodynamicanalysisinforcedconvectiveflowofathirdgradefluidthroughaverticalchannel.Duetothereactivenatureofthefluid,theeffectofinternalheatgenerationisconsideredandassumedtobealinearfunctionoftemperature.ThecouplednonlineardimensionlessordinarydifferentialequationsgoverningthefluidflowaresolvedbyusingtheAdomiandecompositionmethod(ADM).Theeffectsofvariousphysicalparameterssuchasthirdgradematerialparameter,buoyancyparameterandheatgenerationparameteronthethermalstructureofflowarepresentedanddiscussed.

简介：Themomentumequationforsolid-liquidtwo-phaseflowproposedbyElghobashiandAbou-Arabistakenasthegoverningequationsfortheliquidphase,andtheLagrangiandynamicequationforasphericalparticlemovingintheliquidflowasthebasicequationfortherelativemotionoftheparticleintheliquidphaseinthepaper.Thedynamicsequationforabubbleinsolid-liquidtwophaseflowisproposed,aswellasthesimplifiedequationsundertwoextremeconditionswiththerelationshipbetweenthebubblecollapsecharacteristictimeτC*andparticleresponsetimeτrel*beingτC*>>τrel*andτC*<<τrel*.

简介：Thetransientgravitywavesduetoanimpulsivesourceinatwo-layerfluidsystemareinvestigatedanalytically.Thefluidisassumedtobeinviscidandincompressible.Thedensityofeachofthetwolayersisconstant.Fivedifferentboundaryconditionsareconsidered.Thedepthofeachofthetwolayersisinfiniteorfinite.Theupperfluidoffinitedepthiscoveredbyarigidlidorafreesurface.Basedontheassumptionofsmall-amplitudewaves,alinearsystemisestablished.Theintegralsolutionsforthefree-surfaceandinterfacialwavesareobtainedbymeansoftheFourier-Laplacetransform.Thecorrespondingasymptoticrepresentationsarederivedforlargetimewithafixeddistance-to-timeratiobytheStokesandScorermethodsofstationaryphase.Theanalyticalsolutionsshowthattherearetwodifferentmodes,namelythefree-surfaceandinterfacialwavemodes.Thewaveprofilesobserveddependontherelationbetweenthedistance-to-timeratioandthemaximalgroupvelocitiesandonthelimitingvaluesofthesecondderivativesofthefrequenciesaswell.

简介：ANonlinearFluidDamping(NFD)intheformofthesquare-velocityisappliedintheresponseanalysisofVortex-InducedVibrations(VIV).Itsnonlinearhydrodynamiceffectsonthecoupledwakeandstructureoscillatorsareinvestigated.AcomparisonbetweenthecoupledsystemswiththelinearandnonlinearfluiddampingsandexperimentsshowsthattheNFDmodelcanwelldescriberesponsecharacteristics,suchastheamplificationofbodydisplacementatlock-inandfrequencylock-in,bothathighandlowmassratios.Particularly,thepredictedpeakamplitudeofthebodyintheGriffinplotisingoodagreementwithexperimentaldataandempiricalequation,indicatingthesignificanteffectoftheNFDonthestructuremotion.

简介：Thesheet/cloudcavitationisofagreatpracticalinterestsincethehighlyunsteadyfeatureinvolvessignificantfluctuationsaroundthebodywherethecavitationoccurs.Moreover,thecavitatingflowsarecomplicatedduetothethermaleffects.ThepresentpapernumericallystudiestheunsteadycavitatingflowsaroundaNACA0015hydrofoilinthefluoreketoneandtheliquidnitrogenwithparticularemphasisonthethermaleffectsandthedynamicevolution.Thenumericalresultsandtheexperimentalmeasurementsaregenerallyinagreement.Itisshownthatthetemperaturedistributionsarecloselyrelatedtothecavityevolution.Meanwhile,thetemperaturedropismoreevidentintheliquidnitrogenforthesamecavitationnumber,andthethermaleffectsuppressestheoccurrenceandthedevelopmentofthecavitatingflow,especiallyatalowtemperatureinthefluoroketone.Furthermore,thecavitatingflowsarecloselyrelatedtothecomplicatedvortexstructures.Thedistributionsofthepressurearoundthehydrofoilisamajorfactoroftriggeringtheunsteadysheet/cloudcavitation.Atlast,itisinterestingtofindthatoneseesasignificantthermaleffectonthecavitationtransition,asmallvalueofσ/2ɑisrequiredinthethermo-sensitivefluidstoachievethesimilarcavitationtransitionthatoccursinthewater.

简介：Thewaterintakeheadinstalledwithinclinedboardingsiscalledlaminatesedimentprecipitation,whichseparatesliquidandsolidparticlesintwo-phaseflowbygravity.ThepaperpresentstheequationsforcalculatingthedistanceHbetweentwoincllinedboardings,indicatingthatHhasakeyeffectontheparticleprecipitationvelocityV2.Thepaperfocusesalsoonthecal-culationofhydraulicsimilarityofmodelwiththetheoreticmodel.

简介：Thispaperisconcernedwiththewavesgeneratedbya3-Dbodyadvancingbeneaththefreesurfacewithconstantspeedinatwo-layerfluidoffinitedepth.ByapplyingGreen'stheorem,alayeredintegralequationsystembasedontheRankinesourcefortheperturbedvelocitypotentialgeneratedbythemovingbodywasderivedwiththepotentialflowtheory.Afour-nodeisoparametricelementmethodwasusedtotreatwiththesolutionofthelayeredintegralequationsystem.Thesurfaceandinterfacewavesgeneratedbyamovingballwerecalculatednumerically.Theresultswerecomparedwiththeanalyticalresultsforamovingsourcewithconstantvelocity.