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

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

简介：Thispaperpresentsastudyofthemovementandthehydrodynamicperformanceofanewtide-poweredhydraulicturbinethroughnumericalsimulations.Bymeansofthemovingmeshmethod,theopen-closedsequencesofthebladesandthemovementoftherotorsareobtainedandtheangularvelocityandtheaverageenergyutilizationcoefficientunderdifferenttipspeedratiosarealsoobtained.Moreover,theoptimumtipspeedratioisidentifiedbyintegratingtheoutputpowerandtheenergyutilizationcoefficientofthehydraulicturbinewithdifferenttipspeedratios,providingdatasupportfortheprototypedesignofthehydraulicturbine.

简介：Makingfulluseoffunctionalvariationswithvariabledomainforhandlingboththefreesurfaceandunknownpartofthedamwall,afamilyofvariationalprinciples(VPs)forthehybrid(direct-inverse)problemoffreesurfacespillwayflowundergravityisformulatedintermsofthepotentialfunctionΦ.Thistheoryoffersnewrationalandversatilewaysfordamde-signandasoundtheoreticalbasisfornumericalsolution,e.g.bythefiniteelementmethod(FEM).