简介：Thispapergivesemphasisontheresearchoftheproblemoflocalheadlossofcrossfractureflowbyalotofmodelexperiments,andatheoreticalmodeloflocalheadlossofcrossfractureflowisfoundedbyuseofthemomentumlawofwaterflow.Throughthecorrelationanalysisbetweenmodelexperimentalresultsandtheoreticalmodel,thecorrectioncoefficientoftheoreticalmodelisdefinite.Theproposedcalculationformulaoflocalheadlossofcrossfractureflowcanbeusedtoanalyzetheproblemofnetworkfractureseepage.

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简介：Themovementofwaterflowinunsaturatedfracturedrockwasinvestigatedwiththesandstonesamplethroughexperimentalresearchandnumericalsimulation.Theexperimentalresultsshowthatthearrivingtimeofwettingfrontisdelayedbythefracture,resultingintheincreaseofwatersaturationinthedomainontheupstreamsideofthefracture,whichwilllocallyenhancewaterflowthroughthematrix.Thenumericalsimulationwiththefinitevolumemethodcaptureseffectivelythesecharacteristics.Thecomparisonbetweensimulatedandobservedtraveltimeandarrivingtimeofwettingfrontshowsthattheirdifferenceareverysmallandthesimulatedresultsareinagreementwiththeobservedresults,whichimpliescalibratedparametersarereliableandeffective.Thenaccordingtothecalibratedparameters,fracturedmodelswereestablishedtoexaminehowthechangeoflargefracturedaperturewouldaffectthearrivingtimeofwettingfronts,pressureheadsandwatersaturationontheupstreamanddownstreamsidesoffracture.

简介：TheflowthroughasinglefractureisnumericallystudiedbymeansoftheFluentSoftware.Theresultsshowthattheroughnessofthefracturesignificantlyaffectsthehydraulicconductivityinthefractureascomparedwiththecubiclawmodelwidelyusedtodescribetheflowbetweentwosmoothparallelplates.Anewmodelisproposedinthispaper,thenon-symmetricsinusoidalfracturemodel,tosimulatetheflowinarealfracture.Thismodelinvolvestwosinusoidal-varyingwallswithdifferentphasestoreplacetheflatplanesinthecubiclawmodel.Therelationshipsbetweentheeffectivehydraulicaperturesandthephaseretardationfordifferentrelativeamplitudesandwavelengthsarenumericallyinvestigated.Asimpleexpressionoftheeffectivehydraulicapertureofthefractureisobtained,togetherwiththelawoftheeffectivehydraulicapertureagainsttheamplitude,thephaseretardationandthewavelengthoftwosinusoidal-varyingwalls.

简介：Turbiditycurrentsareflowsdrivenbysuspendedsedimentofflood-inducedturbidriverwaterwithexcessdensity.Suchcurrentsareoftenthegoverningfactorinreservoirsedimentationbytransportingfinematerialsoverlongdistancesanddeliveringthemajorityofdeposition,whichthusreducesthestoragecapacity.Therefore,thedesignandoperationofareservoirrequiresanaccuratepredictionofitsoccurrenceconditionandplungingposition,whichistheobjectiveofthepresentstudy.Thisarticlepresentsaverifiedalgebraicslipmixturemodelincludingmomentum,continuityandalgebraicvelocityexpressionstosimulate2-Dturbiditycurrents.Testexperimentsinamultiphaseflumewerecarriedout.Reynoldsnumber,sedimentconcentrationanddensimetricFroudenumberwereusedasparametersintheoccurrenceconditionanalysis.Theplungingofturbiditycurrentsmayproducerefluxandbackflowduetothedivingflowatthesurfaceoftheclearwater.ThesimilarexperimentalresultswerealsoobtainedbyPIVmeasurements

简介：Thispaperinvestigatestheswimmingperformanceoffishundulatorymotionwhichisthebasicforminlocomotionofaquaticalanimalfromahydrodynamicspointofview.Inparticular,thepropulsivecharacteristicsisdiscussed.Thethree-dimensionalpotentialflowoveramodelrectangularflexibleplateperformingthemotionwhichconsistsofaprogressivewaveofagivenwavelengthandphasevelocityalongthechordistreated.Vortexringmethodisusedtocalculatethethrust,thepowerrequiredandthehydrodynamicpropulsiveefficiency,etc.Thedependenceoftheseenergeticsoncertainphysicalparameters,suchastheaspectratio,thereducedfrequencyandthewavenumber,isdiscussed.Itisfoundthatasthewavetengthgetsclosetothebodylength,propulsiveperformanceisnolongersensitivetotheaspectratio.Somequalitativeexplanationofthefishswimmingphenomenaisalsogiven.

简介：Aprocessfornumericalanalysisofradialcirculationdistributionofpropellerbladeisproposedandpresented.Itisbasedontheresultsofnumericalsimulationofthevelocityfieldaroundpropellerbladesandinthewake.Thewell-knowntraditionalmethodusingtangentialvelocitydatainthewakeandapplyingStockes'stheoremwasalsoexaminedintheinvestigation.Theresultsfromtwoapproachesarecomparedwitheachother.Itisfoundthatifthetraditionalwayisutilized,inmanycasesanunexpected'hump'appearsinthecirculationdistributionatcertainouterradius.Theauthorscalculatedthecirculationsdirectlyaroundbladesections,anditisreferredasdirectmethod.Theunexpectedhumpofthecirculationdistributiondisappearsintheresultsofdirectmethod.Thisarticlealsodiscussesthereasonsoftheappearanceoftheunexpectedhumpintraditionalapproach.Thedirectmethodisproposedtohaveapotentialinanalyzingorverifyingtheradialroaddistributionfordesignedpropellerandthenumericalanalysisinsteadofexperimentalvalidationforcirculationdistributioncanbeasatoolinthepropellerdesignprocess.

简介：ThispaperinvestigatesnumericallytheinherentirreversibilityinunsteadygeneralizedCouetteflowbetweentwoparallelplateswithvariableviscosity.ThenonlineargoverningequationsarederivedfromtheNavier-Stokesequationsandsolvednumericallyusingasemi-discretizationfinitedifferencemethodtogetherwiththeRunge-Kutta-Fehlbergintegrationscheme.Theprofilesofvelocityandthetemperatureobtainedareusedtocomputetheentropygenerationnumber,Bejannumber,skinfrictionandNusseltnumber.Theeffectsofembeddedparametersonentireflowstructurearepresentedgraphicallyanddiscussedquantitatively.

简介：Ananalyticalsolutionispresentedfortheradiationandthediffractionofacylindricalbodywithamoonpoolfloatingonthesurfaceofwaterwithafinitedepth.Theexpressionsforthepotentialsareobtainedbythemethodofseparationofvariables,andtheunknowncoefficientsaredeterminedbytheboundaryconditionsandthematchingrequirementsontheinterface.Theeffectsofthemoonpoolonthehydrodynamiccharacteristicsofthebodyareinvestigated.Somepeaksareobservedonthecurvesoftheaddedmassanddampingcoefficients,correspondingtotheresonantfrequenciesofthemoonpool.Theinternalfreesurfacemoveslikeapistonatacertainlowresonantfrequency.

简介：这研究的目的是在昆虫的前面的飞行进入物理卓见到不稳定的力量和相关机制。在前面的飞行的不稳定的力量被学习，基于有在一致流动的震荡的翻译和旋转的陪衬的一个虚拟模型问题，由解决有一个有限元素方法的二维的不可压缩的海军司烧方程。包括进展比率，击飞机的使倾向的角度，击振幅，和搭攻击的角度的振幅，典型参数的效果在力量和流动结构上被分析。

简介：Inthispaperthefiniteelementmethodisusedtosolvethetwo-dimensionalgradi-entcurrentproblem,Thesolutionisobtainedbytwo-stepexplicitmethod.ItisverifiedwithgoodagreementbythefielddataofferedbyXiamenE.P.A.,Fujian,P.R.C.Theauthorsrec-ommendthattheproposedmethodissuitablefortheanalysisandcomputationoflongwavesofepeiricseaattheseawardfirth.

简介：Thisarticlepresentsaspectralanalysisofwaveupliftloadsonahorizontaldeck.Thewaveupliftforcespectrumontheundersideofthedeckisobtained.Itisshownthatthewaveupliftforcespectraldensitydecreaseswiththeincreaseoftherelativeclearance1/3Δh/H.Theinfluencesofdifferentincidentwaveparameters,includingtherelativewaveheight1/3H/d,therelativedeckwidth/sBLandtherelativeclearance1/3Δh/Honthedimensionlesszerothspectralmomentoftheupliftforcesarediscussed.Itisfoundthatthezerothspectralmomentoftheupliftforcesincreaseswiththeincreaseoftherelativewaveheight1/3H/d,anddecreaseswiththeincreaseoftherelativeclearance1/3Δh/H.Anewdimensionlesspredictionmodelforthezerothspectralmomentofwaveupliftloadsonthedeckisproposedandtherelationshipbetweenthewaveupliftforcesandthezerothspectralmomentoftheupliftforceareobtained.

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简介：Inthispaper,thephenomenononcollapsibletubedisplacementoscillation,anewbehaviorofthecollapsibletubepuisatileflowhasbeenstudied.Theexperimentsshowthatthecollapsibletube,inwhichtheflowisperiodicpuisatileintheupstream,willoscillateasasimplesupportedbeamwhenitiscollapsedtocertainextent,andthatifthetubeiscollapsedcontinue,thisoscillationwilltendtoweakandcompletelydisappearlastly.Ananalyticalmodelcorrespondingtothecollapsibletubedisplacementoscillationanditsgovernedequationsaresetupfromtheexperimentbackground.Byanalysingthemodelandsolvingtheequations,thecollapsibletubedisplacementoscillationpatternandtheoscillationoccurringordisappearingcriterionareobtained.Theresultspredictedbythisstudyareinagreementwiththoseobservedfromexperimentphenomena.

简介：Thevelocitiesofboundarylayerflowsbetweentwoparalleloscillatingplatesseparatedbysmalldistance,i.e.,insocallednarrowchannel,weretheoreticallyandexperimentallystudied.ThefocuswasonthelaminarcasewheretheReynoldsnumberReAismuchsmallerthanthetransitionvalue.ThetheoreticalanalysisoftheStokeslayerinoscillatingflowoveranarrowchannelwasmadefirst.ThenLaserDopplerVelocimeter(LDV)wasemployedtomeasuretheStokesboundarylayeraboveanoscillatingflatplateandinsidetheoscillatingnarrowchannelatvariousReHnumbers.Atthesametime,thephaseangledifferencealongtheverticaldirectioninbothanalysisandexperimentwereprovided.Thegoodagreementsareshownbetweenthemeasuredresultsandthetheoreticalsolution.

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

简介：Astochasticmodelwasdevelopedtosimulatetheflowinheterogeneousmediasubjecttorandomboundaryconditions.ApproximatepartialdifferentialequationswerederivedbasedontheKarhunen-Loeve(KL)expansionandperturbationexpansion.Theeffectofrandomboundaryconditionsonthetwo-dimensionalflowwasexamined.Itisshownthattheproposedstochasticmodelisefficienttoincludetherandomboundaryconditions.Therandomboundariesleadtotheincreaseofheadvarianceandvelocityvariance.Theinfluenceoftherandomboundaryconditionsonheaduncertaintyisexertedoverthewholesimulatedregion,whiletherandomnessoftheboundaryconditionsleadstotheincreaseofthevelocityvarianceinthevicinityofboundaries.

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简介：为在调查的飘动的plateare附近的二维的流动的水动力学特征。在大雷纳兹数字近似下面，流动被假定是combinationof外部潜在的流动和薄旋涡层，它由边界层和shedfree组成砍层。为描述外部不稳定的potentialflow的非线性的数学明确的表达结合了一个不稳定的边界层方程为内部粘滞邻近thewaving板的流动被开发。有在thetrailing边强加的一个非线性的Kutta条件的一个半分析的方法被用来解决外部流动和进化的速度领域由一个大振幅的飘动盘子弄醒vortexinduced。不稳定的边界层方程是解决的byextendingPohlhausen“s方法到它的不稳定的对应物。戳并且粘滞拖系数，推进的效率，和模式醒来旋涡表被讨论。

简介：Thepartiallyfilledpipeflowsencounteredindrainagesystemsbelongtoafamilyofunsteadyflowproblemscapableofnumericalsolutionviathemethodofcharacteristics.Thedefiningequationsintermsofflowdepth,velocityandsurfacewavespeedaredevelopedandnumericallysolvedbycharacteristic-differencemethodwithtime-lineinterpolationscheme.Boundaryconditionsforinflow,outflow,movinghydraulicjumpandjunctionsaredevelopedbothexperimentallyandnumerically.Fullscalemodelexperimentswerecarriedoutanditwasconsequentlyclarifiedthatnumericalmodeliscapableofpredictingflowcharacteristicsinrealisticdrainagenetworks.