简介：CoupleddynamicanalysisoftheDeepDraftMulti-Spar(DDMS)platformandthemooringsystemundertheactionofwavesandcurrentiscarriedoutinthetimedomain.Usingageometricallynonlinearfiniteelementmethod,themooring-linedynamicsissimulatedbasedonthetotalLagrangianformulation.WavegroupsareobtainedbytheJONSWAPspectrumandanempiricalwaveenvelopespectruminvolvingtwoenvelope-basedfactorsGroupHeightFactor(GFH)andGroupLengthFactor(GLF).Theresultsshowthatthewavegroupshaveasignificanteffectonthemotionresponsesoftheplatformandthemooringlinetensions.

简介：Thesimulationsofnonlinearsloshinginbothtwo-dimensionalandthree-dimensionalliquidtankswithporositygirderarecarriedoutintimedomainbyusingtheMulti-domainBoundaryElementMethod(MBEM).Thecomparisonofthepresentresultsandthereferencesisconductedandshowstheyagreewellwitheachother.Thethree-dimensionaleffectandtheinfluenceofthewidthofliquidtankandtheheightandporosityofthegirderonthenaturalperiodofthemodelarealsodiscussed.

简介：Theinitiationofpipelinespanninginvolvesthecouplingbetweentheflowoverthepipelineandtheseepage-flowinthesoilunderneaththepipeline.Thepipelinespanninginitiationisexperimentallyobservedanddiscussedinthisarticle.Itisqualitativelyindicatedthatthepressure-dropinducedsoilseepagefailureisthepredominantcauseforpipelinespanninginitiation.Aflow-pipe-seepagesequentialcouplingFiniteElementMethod(FEM)modelisproposedtosimulatethecouplingbetweenthewaterflow-fieldandthesoilseepage-field.Acriticalhydraulicgradientisobtainedforobliqueseepagefailureofthesandinthedirectiontangenttothepipe.Parametricstudyisperformedtoinvestigatetheeffectsofinflowvelocity,pipeembedmentonthepressure-drop,andtheeffectsofsoilinternalfrictionangleandpipeembedment-to-diameterratioonthecriticalflowvelocityforpipelinespanninginitiation.Itisindicatedthatthedimensionlesscriticalflowvelocitychangesapproximatelylinearlywiththesoilinternalfrictionangleforthesubmarinepipelinepartially-embeddedinasandyseabed.

简介：Anumericalanalysisofnon-Newtonianfluidflowinnon-planararterywithbifurcationwasperformedbyusingafiniteelementmethodtosolvethethree-dimensionalNavier-Stokesequationscoupledwiththenon-Newtonianconstitutivemodels,includingCarreau,CrossandBinghammodels.Theobjectiveofthisstudyistoinvestigatetheeffectsofthenon-Newtonianpropertiesofbloodaswellascurvatureandout-of-planegeometryinthenon-planardaughtervesselsonthevelocitydistributionandwallshearstress.Theresultsofthisstudysupporttheviewthatthenon-planarityofbloodvesselsandthenon-Newtonianpropertiesofbloodareofimportantinhemodynamicsandplayasignificantroleinvascularbiologyandpathophysiology.

简介：Thetransientflowmathematicalmodelofarbitraryshapedheterogeneousreservoirswithimpermeabilitybarrierisproposedinthispaper.Inordertoestablishthismodel,theperturbationmethodisemployedandthesolutionofmodelisexpandedintoaseriesinpowersofperturbationparameter.ByusingtheBoundaryElementMethod(BEM)andDuhamelprinciple,wellborepressurewitheffectsofskinsandwellborestorageisobtained.Thetypecurvesareplottedandanalyzedconsideringeffectsofheterogeneity,arbitraryshapeandimpermeablebarriers.Finally,theresultsobtainedbyperturbationboundaryelementmethodiscomparedwiththeanalyticalsolutionandisavailableforthetransientpressureanalysisofarbitraryshapedreservoirs.

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简介：Toclarifytheinfluencesofthetipclearanceflowsontheunsteadycavitatingflow,thethree-dimensionalunsteadycavitatingflowsthroughboththetwo-dimensionalcascadesandthethree-dimensionalinducerwithandwithouttipclearanceareperformednumerically.ThegoverningequationsforthecompressiblefluidflowwiththeDESturbulencemodelareemployedwiththeassumptionoftheisentropicprocessofliquidphase.Theevolutionofcavitiesisrepresentedasthesource/sinkofvaporphase.Thebasicequationsinthecurvelinearcoordinatearesolvedbythefinitedifferencemethod.Astheresultsofthethree-dimensionalcavitatingflowsthroughthetwo-dimensionalcascades,thetipclearanceflowsfromthepressuresidetothesuctionsideofthebladeproducesthetipvortexcavitation,whichaffectsthesheetcavitationontheleadingedgeofthenextbladeandenhancestheblockageeffectnearthecasingthantheflowswithouttipclearance.Ontheotherhand,inthecaseofthethree-dimensionalinducer,thelargebackflowcavitationisobservedaroundtheinletoftheinducer,wherethecavitiesaredevelopedonthecasingbythetipclearanceflows.Thelargepressuregradientbetweenthenon-cavitatingpressuresideandthecavitatingsuctionsideenhancesthetipclearanceflows.Thecalculationconsideringthetipclearancereproducesthedevelopedcavitationregionsimilartothatofexperimentalvisualizations.Additionally,thebackflowcavitationrotateswiththespeedslowerthantherotationspeedoftheinducer.Then,therotationofbackflowcavitationcausestheperiodicfluctuationoftheoutletpressuregreaterthanthatoftheinletpressure.

简介：TheunsteadycavitationevolutionaroundtheClark-Yhydrofoilisinvestigatedinthispaper,byusinganimprovedfilter-basemodel(FBM)withthedensitycorrectionmethod(DCM).Toimprovethepredictionaccuracy,thefilterscaleisadjustedbasedonthegridsize.Thenumericalresultsshowthatasmallfilterscaleiscrucialfortheunsteadysimulationsofthecavitysheddingflow.ThehybridmethodthatcombinestheFBMandtheDCMcouldhelptolimittheoverpredictionoftheturbulentviscosityinthecavitationregiononthewallofthehydrofoilandinthewake.Thelargevalueofthemaximumdensityratio?l/?v,clippromotesthemasstransferratebetweentheliquidphaseandthevaporphase,whichresultsinalargesheetcavitylengthandthevaporfractionriseinsidethecavity.Thecavitypatternspredictedbytheimprovedmethodareverifiedbytheexperimentalvisualizations.Thetime-averagelift,thedragcoefficientandtheprimaryoscillatingfrequencyStforthecavitationnumber?=0.8,theangleofattack,?=8o,ataReynoldsnumberRe=7?105are0.735,0.115and0.183,respectively,andthepredictederrorsare3.29%,3.36%and8.93%.Thetypicalthreestagesinonerevolutionarewell-captured,includingtheinitiationofthesheet/attachedcavity,thegrowthtowardthetrailingedge(TE)withthedevelopmentofthere-entrantjetflow,andthelargescalecloudcavityshedding.ItisobservedthatthecloudcavitysheddingflowinducesthevortexpairsoftheTEvorticesinthewakeandthesheddingvortices.Thepositivevorticityvortexofthere-entrantjetandtheTEvorticesinteractsandmergeswiththenegativevorticityvortexoftheleadingedge(LE)cavitytoproducethesheddingflow.

简介：Axisymmetricliquidjetshavebeenstudiedextensivelyformorethanonecentury,whilenon-axisymmetricjetsarealsoverycommoninengineeringapplicationsbutattractlessconcern.BasedonEulerianfluid-fluidmodelinFluentsoftware,thisarticleanalysizesthe3-DflowfieldsofpressureatomizerswithV-shapedcutatorifice,whichwillresultinanon-axisymmetricliquidjet.Flowrateanalysisandjetstructureanalysisarecarriedout,theresultsshowthattheflowratecanbeformulatedbyaddingacorrectioncoefficienttotheformulaofinviscidaxisymmetricjetsinatomizationregime,whentheWebernumberislowenoughtomaketheflowfalloutofatomizationregime,andthejetstructuretogetherwiththeflowrateformulawillchange.Analysisshowsthattheevolutionofthesprayandthereforethestructureoftheliquidjetareaffectedmuchbyrelativevelocityandthelocalvolumefractionofliquidphase.

简介：Flowdistributionheadersplayamajorroleinheatexchangers.Theselectionofheaderdiameter,branchpipediameter,branchpipespacingetc.isbasedonthedesigner'sexperienceandgeneralguidelines.Theproperselectionoftheheaderdimensionswillyielduniformflowdistributioninheatexchangers,whichinturnwillenhancetheheatexchangerefficiency.Inthiswork,theflowdistributioninbranchpipesandthepressurevariationacrossthebranchpipesinlaminarandlowturbulenceregionisstudiedwithtwomodelsoftheinletdividingheaders.Whenthenumericalanalysishasbeenapplied,itsinabilitytopredictthenoflowconditionthroughthebranchpipesisrevealed.Theresultsarepresentedintheformofflowrateratiothroughbranchpipesandnondimensionalcoefficientsacrossbranchpipeswhichareusefultoapplytheexistingmathematicalmodelsforthepresentexperimentalsetup.

简介：Adimpleappearsonafreesurfacewhilerotatingacylindertankfilledwithliquid.Thedimplestartstoconcentricallydeepertoadrainportatthebottomcenterofthetank.Overtime,thedimplepenetratesthedrainport,afreesurfaceformsalongandslenderstringshapeinthetank,andaso-calledvortexing(aircore)phenomenonoccurs.Thegenerationofavortexcoredependsonthesizeofthetankanddrainport,andonthepropertiesoftheliquidinthetank.Inthisstudy,theliquidlevelandthetimeatwhichthevortexcoreisinitiallygeneratedarenumericallyinvestigatedusingdifferentvaluesoftankdiameter,drainportdiameter,andinitialtankrotationalspeeds.Insteadofafullthree-dimensionalanalysis,atwo-dimensionalaxisymmetricsimulationisconducted.Themomentumconservationequationinthecircumferentialdirectionisadditionallysolvedinthetwo-dimensionalmeshsystem.Severalnon-dimensionalvariablesarecreated:theratiooftheaircoregenerationdistanceandtankdiameter,thediameterratioofthetankanddrainport,therotationalReynoldsnumber,therotationalFroudenumber,andtherotationalWebernumber.Finally,thenon-dimensionalaircoregenerationdistanceiscorrelatedwiththeothernon-dimensionalparameters.

简介：Thepurposeofthispaperistofindsomebettermethodsforcalculatingin-lineforcesonaverticalcircularcylinderandforanalysingthehydrodynamiccoefficientsC_DandC_Minwave-currentco-existingfield.Inthispa-per,inordertocalculatehydrodynamicforces,theauthorstrytofindawayofapplyingagreatnumberofthere-sultsaboutC_DandC_Mforwave-onlyfieldinthecaseofwave-currentco-existingfield,andtheresultsaboutC_DandC_Mobtainedinregularwavesintheeaseofirregularwaves.Suchawaymaybeofsignificanceinengineeringandfurtherresearch.