简介：Basedonthepropertiesoftraffic,macroscopicdynamicequationsaresetuptosimulatetheflowoftraffic.Besidesrelaxationtermandcompressibilityterm,achangeableareatermiscomposedinthemodeltodescribetheeffectofcarparking,tollbooth,trafficincidents,roadgradingandbicyclesontrafficflow.Withnumericalmethod,threecasesarepresentedtosimulatethechanginglaneareawithtimeandspaceandthepropagatingprocessofhightrafficdensity.Theresultsshowthatthedynamicmodelcanreasonablydescribetheevolutionoftrafficstatesinvariouscomplicatedoccasions.

简介：Freesurfaceflowproblemsinvolvinglargefreemotionsareanalysedusingfiniteelementtechniques.InsolvingtheseproblemsanArbitraryLagrangian-Eulerian(ALE)kinematicaldescriptionofthefluiddomainisadopted,inwhichthenodalpointscanbedisplacedindependentlyofthefluidmotion.Anewmeshtracingmethodisproposedinthispaper.Toconfirmtheeffectivenessofthenewmethod,solitarywavepropagationisanalysedandthenumericalresultsarecomparedwiththeanalyticalresults.ThebehaviouroftheviscousfluidflowwithafreesurfaceisexpressedbytheunsteadyNavier-Stokesequation.Fornumericalintegrationintimethevelocitycorrectionfractionalstepmethodisused.

简介：Lyapunov'ssecondmethodwasusedtostudythenonlinearstabilityofparallelshearflowsforstress-freeboundaries.Byintroducinganenergyfunctional,itwasshownthattheplaneCouetteandplanePoiseuilleflowsareconditionallyandasymptoticallystableforallReynoldsnumbers.Inparticular,totwo-dimensionalperturbations,bydefiningnewenergyfunctionalstheunconditionalstabilityofthebasicflowswasproved.

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简介：Channelfrictionisanimportantparameterinhydraulicanalysis.AchannelfrictionparameterinversionmethodbasedonKalmanFilterwithunknownparametervectorisproposed.Numericalsimulationsindicatethatwhenthenumberofmonitoringstationsexceedsacriticalvalue,thesolutionishardlyaffected.Inaddition,KalmanFilterwithunknownparametervectoriseffectiveonlyatunsteadystate.Forthenonlinearequations,computationsofsensitivitymatricesaretime-costly.Twosimplifiedmeasurescanreducecomputingtime,butnotinfluencetheresults.Oneistoreducesensitivitymatrixanalysistime,theotheristosubstituteforsensitivitymatrix.

简介：InspiredbyDryobalanopsaromaticaseed,anewbiomimicrymarinecurrentturbineisproposed.Hydrodynamicperformanceandwakepropertiesaretwokeyfactorsdeterminingwhetheranewmarinecurrentturbinedesignispracticalornot.Thus,astudyofhydrodynamicperformanceandwakeoftheproposedbiomimicryturbineisconducted.Thecomputationalfluiddynamics(CFD)software,OpenFOAMisusedtogeneratetherequiredresultsforthementionedstudy.ThehydrodynamicperformanceandwakepropertiesoftheproposedbiomimicryturbineiscomparedtotwoconventionalturbinesofBahajetal.andPinonetal.respectively.Thesimulationresultsshowedthattheproposedbiomimicrymarinecurrentturbinegivesoptimumpoweroutputwithitspowercoefficient,0.376PC≈atthetipspeedratio(TSR)of1.5.Underthesameboundaryconditions,themaximumtorqueproducedbytheproposedbiomimicryturbineatzerorotationalspeedis38.71Nmwhichis1110%greaterthanthetorquegeneratedbytheturbineofBahajetal..Therecoverydistanceforthewakeofthebiomimicryturbineispredictedtobe10.6%shorterthanthatofIFREMER-LOMCturbine.Theabove-mentionedresultsconfirmthepotentialapplicationoftheproposedbiomimicrymarinecurrentturbineintherenewableenergyindustry.

简介：AGalerkinfiniteelementformulationisdevelopedforthenumericalsimulationofwaterflowinvariablysat-uratedporousmedia,Picardalgorithmisusedtodealwithseverelynonlinearfieldproblems.Thealgorithmisfor-mulatedforarbitraryquadrilateralelementswhichcanaccommodatecomplexgeometry.Anew"influencecoeffi-cient"techniqueisdevelopedwhichcanbeusedtocomputeelementmatricesinasimpleandefficientmanner.Thistechniqueavoidsnumericalintegrationandleadstoasubstantialsavingofcost.Twoexamplesarepresentedtoverifytheproposedmethod.

简介：Thepapermainlyfocusesondescribingthemodificationmadetoanewdepth-averagedtwo-equationturbulentclosuremodelbasedontherevisedκ-ωmodelrecently.Inthecaseofsidedischargedjetswithtempera-turedifferenceandtransversecurrent,thenewmodelhasbeeninvestigatednumericallyindetail.Asapracticalexampleofapplicationtousethenewmodel,thesidedischargeofthecoolingwaterfromthreeoutletsintoanatu-ralriverononebankhasbeensimulated,andthegeomorphicvariationunderwaterhasbeentreatedsuitably.Twodepth-averagedmodels,andhavebeenused,thelaterwastheuniqueoneuptothepresent.Emphasisisplacedonthecomparativeresearchwithdifferentmodelsunderthesamecomputationalconditions.Ithasbeenverifiedthatifthedischargedflowratesarerelativelysmall,whenthepollutantplumeinthenearandtransitionalzonsispredicted,theagreementwithexperimentalandfielddatasimulatedbythemodelisbetterthanbythemodelorothermethodscommonlyusedinengineering.