简介：Laminarheattransferproblemisanalyzedforadiskrotatingwiththeangularspeedωinaco-rotatingfluid(withtheangularspeedΩ).Thefluidisswirledinaccordancewithaforced-vortexlaw,itrotatesasasolidbodyatβ=Ω/ω=const.Radialvariationofthedisk’ssurfacetemperaturefollowsapowerlaw.Anexactnumericalsolutionoftheproblemisobtainedbasingontheself-similarprofilesofthelocaltemperatureoffluid,itsstaticpressureandvelocitycomponents.NumericalcomputationsweredoneatthePrandtlnumbersPr=1(?)0.71.Itisshownthatwithincreasingβbothradialandtangentialcomponentsofshearstressesdecrease,andtozerovalueatβ=1.Nusseltnumberispracticallyconstantatβ=0(?)0.3(andevenhasapointofamaximuminthisregion);Nudecreasenoticeablyforlargerβvalues.

简介：Anewflowtheoryisestablishedthroughtheobjectivityrequirementonthefluiddynamics.Itwasknownthatinhomogeneousfluidmotiongaverisetoviscousforcewhiletheselectionofobserversondifferentspace-timepointswouldchangesuchaninhomogeneouscharacter.Therefore,whentheviscousforcewasconsideredasanobjectiveexistenceforeigntotheselectionofobservers,theforminvariancesofviscousforceandmomentumequationunderlocalrotationtransformationrequiredanewdynamicfield,namelythevortexfieldtobeintroduced.ThenthedynamicalequationsofallflowfieldswereobtainedthroughconstructingtheLagrangiandensityoffluidsystemandusingthevariationalapproachofenergy.

简介：WithoutsimplifyingtheN-SequationsofGermano’s,westudytheflowinahelicalcircularpipeemployingperturbationmethod.Athirdperturbationsolutionisfullypresented.Thefirst-second-andthird-ordereffectsofcurvatureкandtorsionтonthesecondaryflowandaxialvelocityarediscussedindetail.Thefirst-ordereffectofcurvatureistoformtwocounter-rotatingcellsofthesecondaryflowandtopushthemaximurnaxialvelocitytotheouterbend.Thetwocellsarepushedtotheouterbendbythepuresecond-ordereffectofcurvature.Thecombinedhigher-order(second-,third-)effectsofcurvatureandtorsion,arefoundtobeanenlargementofthelowervortexofthesecondaryflowatexpenseoftheupperoneandaclockwiseshiftofthecentersofthesecondaryvorticesandthelocationofmaximumaxialvelocity.Whentheaxialpressuregradientissmallenoughorthetorsionissufficientlylargerthanthecurvature,thelocationofthemaximalaxialvelocityisneartheinnerbend.Theequationofthevolumefluxisobtainedfromintegratingtheperturbationsolutionsofaxialvelocity.Fromtheequationthevalidityrangeoftheperturbationsolutionsinthispapercanbeobtainedandtheconclusionthatthethreetermsoftorsionhavenoeffectonthevolumefluxcaneasilybedrawn.Whentheaxialpressuregradientislessthan22.67,thevolumefluxinahelicalpipeislargerthanthatinastraightpipe.

简介：Theflowcharacteristicsinaspouted-fluidbeddifferfromthoseinspoutedorfluidizedbedsbecauseoftheinjectionofthespoutinggasandtheintroductionofafluidizinggas.Theflowbehaviorofgas-solidphaseswaspredictedusingtheEulerian-Euleriantwo-fluidmodel(TFM)approachwithkinetictheoryforgranularflowtoobtaintheflowpatternsinspouted-fluidbeds.Thegasfluxandgasincidentanglehaveasignificantinfluenceontheporosityandparticleconcentrationingas-solidspouted-fluidbeds.Thefluidizinggasfluxaffectstheflowbehaviorofparticlesinthefountain.Inthespouted-fluidbed,thesolidsvolumefractionislowinthespoutandhighintheannulus.However,thesolidsvolumefractionisreducednearthewall.

简介：Thepaperstudiestheproblemoffluidflowandfluidshearstressincanaliculiwhentheosteonissubjecttoexternalmechanicalloadingandbloodpressureoscillation.Thesingleosteonismodeledasasaturatedporoelasticcylinder.Solidskeletonisregardedasaporoelastictransverselyisotropicmaterial.Togetnear-realisticresults,boththeinterstitialfluidandthesolidmatrixareregardedascompressible.BloodpressureoscillationintheHaveriancanalisconsidered.Usingtheporoelasticitytheory,ananalyticalsolutionoftheporefluidpressureisobtained.Assumingthefluidincanaliculiisincompressible,analyticalsolutionsoffluidflowvelocityandfluidshearstresswiththeNavier-Stokesequationsofincompressiblefluidareobtained.Theeffectofvariousparametersonthefluidflowvelocityandfluidshearstressisstudied.更多还原

简介：wellposedness问题为一各向异性不可压缩粘滞在3的液体，在向量B附近旋转(t，x):=(b1(t，x)，b2(t，x)，b3(t，x))，被学习。在同类的案例中的全球wellposedness(B=e3)与在空间B0的足够地快的旋转，？被证明。在不同类的案例中(B=B(t，xh))，在B0的答案的全球存在和唯一，？被获得，如果起始的数据是足够的与水平粘性相比小。而且，我们在一样的函数空格获得解决方案的一致本地存在和唯一。我们也在B2,1获得整齐的繁殖吗？在另外的假设下面，那B仅仅取决于一个水平空间变量。

简介：

简介：所有液体动态方程在他们的当模特儿的规模下面是有效的，意味着免费路径例如粒子并且意味着Boltzmann方程的碰撞时间规模和NavierStokes(NS)方程的水动力学规模。当前的计算液体动力学(CFD)集中于部分微分方程(PDE)的数字答案，并且它的目的是得到这些管理方程的精确答案。在如此的一个CFD惯例下面，它是难的开发盖住流动物理从的一个统一计划对水动力学运动因为没有能用Boltzmann做光滑的转变到当模特儿的NS的如此的管理方程，连续地可伸缩。液体动力学的学习需要超出传统的数字部分微分方程。出现设计应用程序，例如为近空间的飞行和流动和热转移在的空气车辆设计微设备，确实要求煤气的动力学的概念的进一步的扩大到物理现实，而非传统的可区分的管理方程的更大的域。在当前的阶段，非平衡流动物理很好还没由于适当工具的缺乏被探索了或清楚地理解。不幸地在当前的数字PDE途径下面，它是难的由于有效PDE的缺席开发如此的一个有意义的工具。以便多尺度的构造和类似于构造管理方程的Boltzmann或NS的当模特儿的过程的multiphysics模拟方法，一个数字算法的发展应该基于物理建模的第一个原则。在这份报纸，而不是跟随传统的数字PDE路径，我们介绍为CFD算法开发的作为一个原则的直接建模。因为所有计算与有限房间分辨率在一个discretized空格被进行，要当模特儿的流动物理不得不在网孔尺寸和时间步骤规模被做。这里，CFD是差不多分离数字进化方程的直接构造，在网孔尺寸和时间步骤将玩的地方，在建模的动态角色处理。与在网孔之间的比率的变化，尺寸和本地粒子意味着免费路径，从到水动力学波浪繁殖的运动粒子运输和碰撞的计划愿望俘获流动物理。基于直接建模，流动运动的连续动力学�

简介：Thispaperconsiderstheunsteadyunidirectionalflowofamicropolarfluid,producedbythesuddenapplicationofanarbitrarytimedependentpressuregradient,betweentwoparallelplates.Theno-slipandtheno-spinboundaryconditionsareused.ExactsolutionsforthevelocityandmicrorotationdistributionsareobtainedbasedontheuseofthecomplexinversionformulaofLaplacetransform.Thesolutionoftheproblemisalsoconsiderediftheupperboundaryoftheflowisafreesurface.Theparticula...

简介：Thispaperisconcernedwiththedispersionofparticlesonthefluid-liquidinterface.Inapreviousstudywehaveshownthatwhensmallparticles,e.g.,flour,pollen,glassbeads,etc.,contactanair-liquidinterface,theydisperserapidlyasiftheywereinanexplosion.Therapiddispersionisduetothefactthatthecapillaryforcepullsparticlesintotheinterfacecausingthemtoacceleratetoalargevelocity.Inthispaperweshowthatmotionofparticlesnormaltotheinterfaceisinertiadominated;theyoscillateverticallyabouttheirequilibriumpositionbeforecomingtorestunderviscousdrag.Thisverticalmotionofaparticlecausesaradially-outwardlateral(secondary)flowontheinterfacethatcausesnearbyparticlestomoveaway.Thedispersiononaliquid-liquidinterface,whichistheprimaryfocusofthisstudy,wasrelativelyweakerthanonanair-liquidinterface,andoccurredoveralongerperiodoftime.Whenfallingthroughanupperliquidtheparticleshaveaslowervelocitythanwhenfallingthroughairbecausetheliquidhasagreaterviscosity.Anotherdifferencefortheliquid-liquidinterfaceisthattheseparationofparticlesbeginsintheupperliquidbeforetheparticlesreachtheinterface.Therateofdispersiondependedonthesizeoftheparticles,thedensitiesoftheparticleandliquids,theviscositiesoftheliquidsinvolved,andthecontactangle.Forsmallparticles,partialpinningandhysteresisofthethree-phasecontactlineonthesurfaceoftheparticleduringadsorptiononliquid-liquidinterfaceswasalsoimportant.Thefrequencyofoscillationofparticlesabouttheirfloatingequilibriumincreasedwithdecreasingparticlesizeonbothair-waterandliquid-liquidinterfaces,andthetimetoreachequilibriumdecreasedwithdecreasingparticlesize.Theseresultsareinagreementwithouranalysis.

简介：ThevalidityofNavier'spartialslipconditionisinvestigatedbystudyingtheoscillatoryflowinacoatedchannel.Thetwo-fluidmodelisusedtosolvetheunsteadyviscousequationsexactly.Partialslipisexperiencedbythecorefluid.ItisfoundthatNaviersconditiondoesnotholdforanunsteadycorefluid.

简介：不同液体的混乱混合生产旋绕的结构到分开这些液体的接口。为能溶合的液体(是这里考虑了)，这个接口被定义为50%集体集中isosurface。为导致的冲击波(Richtmyer-Meshkov)不稳定性，我们发现接口当计算网孔被精制，逐渐地复杂。如果Kolmogorov规模相对网孔是小的，这界面的混乱被粘性，或由计算网孔割掉。在集成的接口统计的政体，我们然后检验混合，即集中统计，由质量调整了散开。为比统一显著地大的Schmidt数字，典型地代表液体或稠密的血浆，另外的网孔精炼通常被需要克服数字集体散开并且完成混合问题的一个集成的答案。然而，与前面追踪的利益并且与一个算法，那允许有限接口散开，我们能在Schmidt数字一致地保证集中。我们证明不同答案源于Schmidt数字的变化。我们建议潜水艇格子粘性和可能在现实主义的格子层次允许集成的答案的集体散开parameterizations。

简介：Theanalysisofthesolutionoffluidnetworkmodeliscarriedouttomatchtheneedofgraphicallymodularauto-modellingforpowerplantsimulatorsbecauseofthesymmetryandsparsityofthelinearsystemofequations,anewmethodofimprovedGausseliminationispresentedforthesolutionoflargescalematrices.ComparisonofthenewmethodwiththeclassicalGausseliminationmethod,theGauss-Seideliterativemethodaregiven.Theresultsshowthatthealgorithmprovidedisbetterthantheothersandissuitableforauto-modellingoffluidnetowrksofpowerplants.

简介：Wepresentthesimulationofthedynamicsoffluid-cylinderinteractionsinanarrowthree-dimensionalchannelfilledwithaNewtonianfluid,usingaLagrangemultiplierbasedfictitiousdomainmethodologycombinedwithafiniteelementmethodandanoperatorsplittingtechnique.Asexpected,asettlingtruncatedcylinderturnsitsbroadsideperpendiculartothemainstreamdirectionandthecenterofmassmovestothecentralaxisofthechannel.Inthecaseoftwotruncatedcylinders,theyfirstmovearoundeachotherforawhileandthenstaytogetherina"T"shape.Afterthe"T"shapehasbeenformedforalongenoughtime,wefoundnovortexsheddingbehindthecylinders.Whensimulatingthefluidizationof60truncatedcylinders,wecapturedthefeaturesofinteractionsamongfluidizedcylindersasobservedinexperiments.

简介：Vibrationofacircularmembraneincontactwithafluidhasextensiveapplicationsinindustry.Thenaturalvibrationfrequenciesfortheasymmetricfreevibrationofacircularmembraneincontactwithaboundedincompressiblefluidarederivedinthispaper.Consideringsmalloscillationsinducedbythemembranevibrationinanincompressibleandinviscidfluid,thevelocitypotentialfunctionisusedtodescribethefluidfield.Twoapproachesareusedtoderivethefreevibrationfrequenciesofthesystem,whichincludeavariationalformulationandanapproximatesolutionemployingtheRayleighquotientmethod.Agoodcorrelationisfoundbetweenfreevibrationfrequenciesevaluatedbythesemethods.Finally,theeffectsofthefluiddepth,themassdensity,andtheradialtensiononthefreevibrationfrequenciesofthecoupledsystemareinvestigated.

简介：Thechaotictransientsofacurvedfluidconveyingtubesubjectedtoanonlinearfoundationareinvestigated.TheassumptionoftheinextensibilityofthetubeisappliedtoderivethenonlineardifferentialequationofmotionviatheNewtonianapproach,withthedifferentialquadraturemethodusedtodiscretizethecurvedtubemodelinthespatialdomain.Andthenonlineardynamicmotionequationisobtained.Thenumericalanalysisshowsthat,thefinalsteadystatesaresensitivetotheinitialsystemconditionsinalargeparameterregionofthefluidspeed.Thisphenomenonofchaotictransientsisinfrequentforfluidconveyingtubes.

简介：Theuniquecharacteristicsofgas-solidstwo-phaseflowandfluidizationintermsoftheflowstructuresandtheapparentbehaviorofparticlesandfluid-particleinteractionsarecloselylinkedtophysicalpropertiesoftheparticles,operatingconditionsandbedconfigurations.Fluidizedbedsbehavequitedifferentlywhensolidproperties,gasvelocitiesorvesselgeometriesarevaded.Anunderstandingofhydrodynamicchangesandhowthey,inturn,influencethetransferandreactioncharacteristicsofchemicalandthermaloperationsbyvariationsingas-solidcontact,residencetime,solidcirculationandmixingandgasdistributionisveryimportantfortheproperdesignandscale-upoffluidizedbedreactors.Inthispaper,ratherthanattemptingacomprehensivesurvey,weconcentrateonexaminingsomeimportantpositiveandnegativeimpactsofparticlesizes,bubbles,clustersandcolumnwallsonthephysicalandchemicalaspectsofchemicalreactorperformancefromtheengineeringapplicationpointofviewwiththeaimofforminganadequateconceptforguidingthedesignofmultiphasefluidizedbedchemicalreactors.

简介：Thisworkinvestigatestheflowofathirdgradefluidinarotatingframeofreference.Thefluidisincompressibleandmagnetohydrodynamic(MHD).Theflowisboundedbetweentwoporousplates,thelowerofwhichisshrinkinglinearly.Mathematicalmodellingoftheconsideredflowleadstoanonlinearproblem.Thesolutionofthisnonlinearproblemiscomputedbythehomotopyanalysismethod(HAM).Graphsarepresentedtodemonstratetheeffectofseveralemergingparameters,whichclearlydescribetheflowcharacteristics.

简介：Anexactsolutionisdevelopedforthetimeperiodicelectroosmoticflowofanon-Newtonianfluidbetweenthemicro-parallelplates.TheconstitutiveequationsofageneralizedBurgersfluidareusedinthemathematicalformulation.TheresultingproblemissolvedbyaFouriertransformtechnique.Graphsareplottedanddiscussedforvariousemergingparametersofinterest.

简介：ThesedimentationsoftwocylindricalparticlesinthreedifferentinitialrelativepositionsarenumericallysimulatedusingthelatticeBoltzmannmethod.Themovementcharacteristicsandparticleinteractionsduringtheirsedimentationarepresentedanddiscussedindetail.Theresultsshowthat,(i)ifthetwoparticlesarereleasedparallelbutseparatedhorizontally,theypushawayeachother,rotateinwardsandseparatehorizontallyastheyfall;(ii)ifthetwoparticlesarereleasedparallelbutseparatedvertically,thesedimentationbehaviorcanbeclassifiedintothreestages:trailing,tumblingandseparating;(iii)ifthetwoparticlesarereleasedperpendicularbutseparatedvertically,thesedimentationbehaviorcanbecharacterizedas:trailingandrotating,touchingandsliding.Inordertovalidateoursimulation,experimentswerealsoconductedandtheresultsagreewellwiththenumericalones.