简介:ThispaperinvestigatesnumericallytheinherentirreversibilityinunsteadygeneralizedCouetteflowbetweentwoparallelplateswithvariableviscosity.ThenonlineargoverningequationsarederivedfromtheNavier-Stokesequationsandsolvednumericallyusingasemi-discretizationfinitedifferencemethodtogetherwiththeRunge-Kutta-Fehlbergintegrationscheme.Theprofilesofvelocityandthetemperatureobtainedareusedtocomputetheentropygenerationnumber,Bejannumber,skinfrictionandNusseltnumber.Theeffectsofembeddedparametersonentireflowstructurearepresentedgraphicallyanddiscussedquantitatively.
简介:ThispaperdiscussesthenonlinearstabilitybehaviourofdistortedplaneCouetteflowto2-dimensionaldisturbances,andcomparesitwiththatofdistortedplanePoiseuilleflow.TheresultsshowthatplaneCouetteflowismoreunstablethanplanePoiseuilleflowtofinite-amplitudedisturbances.
简介:ThispaperestablishesthevelocityfieldandtheadequateshearstresscorrespondingtothemotionofanOldroyd-BfluidbetweentwoinfinitecoaxialcircularcylindersbymeansoffiniteHankeltransforms.Theflowofthefluidisproducedbytheinnercylinderwhichappliesatime-dependentlongitudinalshearstresstothefluid.Theexactanalyticalsolutions,presentedinseriesformintermsofBesselfunctions,satisfyallimposedinitialandboundaryconditions.ThegeneralsolutionscanbeeasilyspecializedtogivesimilarsolutionsforMaxwell,secondgradeandNewtonianfluidsperformingthesamemotion.Finally,somecharacteristicsofthemotionaswellastheinfluenceofthematerialparametersonthebehaviorofthefluidmotionaregraphicallyillustrated.
简介:ThispaperinvestigatestheunsteadyhydromagneticCouettefluidflowthroughaporousmediumbetweentwoinfinitehorizontalplatesinducedbythenon-torsionaloscillationsofoneoftheplatesinarotatingsystemusingboundarylayerapproximation.ThefluidisassumedtobeNewtonianandincompressible.Laplacetransformtechniqueisadoptedtoobtainaunifiedsolutionofthevelocityfields.Suchaflowmodelisofgreatinterest,notonlyforitstheoreticalsignificance,butalsoforitswideapplicatio...
简介:ThedissipationfunctioninturbulentplanePoiseuilleflows(PPFs)andplaneCouetteflows(PCFs)subjecttospanwiserotationsisanalyzed.Itisfoundthat,inthePCFswithoutsystemrotations,themeanpartisconstantwhilethefluctuationpartfollowsalogarithmiclaw,resultinginasimilarlogarithmicskinfrictionlawasPPFs.However,iftheflowsystemrotatesinthespanwisedirection,noobviousdependenceontherotationnumbercanbeevaluated.InthePPFswithrotations,thedissipationfunctionshowsanincreasewiththerotationnumber,whileinthePCFswithrotations,whentherotationnumberincreases,thedissipationfunctionfirstdecreasesandthenincreases.
简介:Thelinearstabilityofwall-injectedpressuredrivenCouette-likeflowinpower-lawfluidsisstudied.PreviousstudyonthiskindofflowforNewtonianfluidsbyNicoudandAngilella[Phys.Rev.E56,3000(1997)]wasextendedtopower-lawfluidstounderstandthee?ectsofshear-thinning/thickeningnatureontheflowstability.ArelatedexpressionbetweenthecriticalcrossflowReynoldsnumberforNewtonianfluidsandthatforpower-lawfluidsisobtainedasthestreamwiseReynoldsnumberislargeenoughbasedonnumericalcomputations,andverifiedtheoreticallyinthecaseofalimitingconditionwiththepower-lawindex.
简介:Inthispaper,theflowpatternsobservedinhorizontalCouette-Taylorflow(CTF)werecorrelatedusingdimensionlessnumbers.Theanalysisoftheresultsshowedthatthestructureoftheflowwasanoutcomeofinteractionbetweenfluidinertiarelatedtoaxialandrotationalflowsandgravitation.Therefore,theflowstructureswerecorrelatedusingaxialandangularReynoldsnumbers,andArchimedesnumberforthegivenvalueofgas-to-liquidflowratio.Finally,thecorrelationforthepredictionofthetransitiontotheflowregimeobservedathighrotationalspeedswasproposed.ThecomparisonwithexperimentscarriedoutintheverticalCTFfromtheliteratureshowedthatthiscorrelationcanalsobeusefulinthecaseofverticalflow.
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