简介：TheresponseoftheSouthChinaSea(SCS)toTyphoonChanchu(2006)wasexaminedusingtheMM5andPOMmodel.InthePOMmodel,seasurfaceboundaryconditionswereforcedbythesimulationwindfieldfromMM5,thevelocityforcingwasintroducedintheeasternboundaryandthecomputationalschemesofheatfluxesatthesurfacewereintroduced.Comparisonwiththeobservationdatashowsthatthesimulatedresultsarereliable.IntheresponseprocessoftheSCStoTyphoonChanchu,theinfluenceoftheheatfluxesonthermalstructureoftheSCSwasregionallydifferent.Strongwindforcingwouldleadtoupwellingphenomenoninthelateralboundaryofdeepwaterbasin.Furthermore,theEkmanpumpingtheorywasusedtodiscusssubsurfaceupwellinganddownwellingphenomenonintyphoonforcedstage.

简介：Theacousticperformanceofthestructureformeasuringcavitationnoiseistheoreticallyanalysed,andtwojudgingcriteriaoftheacousticperformanceofSTW（soundtransmissionwindow）arepresentedinthispaper.OneisofimpedancematchingbetweenworkingliquidandSTW:ρ1C1=ρ2C2.Theotherisofmaximumfrequency（orminimumwavelength）ofcavitationnoisespectrum:fmax≤c/60D(orλmin/D≥60).Ifeitherofthecriteriaismetreliablemeasuredresultsofcavitationnoisewillbeobtained.Thetheoreticalresultsareverifiedthroughexperi-ments.Accordingtothecriteria,thepaperanalysestheacousticperformanceofroutinelyusedplexiglassSTW.Theresultsshowthatintheresearchofclearwatercavitationtheimpedanceratio,2.18,doesnotsatisfyρ1C1=ρ2C2,andfmax≤C/60Dhardlyholdsforactualcavitationnoisespectrum.Therefore,plexiglassSTWisnotgoodenoughforsoundtransmission.Fromthispointofview,polyethyleneisbettersoundtransmissionmaterialthanplexi-glass.

简介：Usingtime-dependentcompressiblelaminarNavier-Stokesequationswithafinitevolumemethodincorporatingathird-order-accuratediscretizationscheme,theflowstructuresaroundaslenderatcertainincidencesarenumericalsimulatedandtypicalcrossflowpatternsarepresented.Atincidence10°,thesevorticalconfigurationsaredifferentatdissimilaraxiallocationsthoughtheyaresymmetric.At35°,thesymmetricvorticalstructuresstillmaintainovertheslender,yettheirinteractionatafterbodyisintensethanthatattheforebodysincethetwovorticeshavefullydevelopeddownstream.Theunstabletopologicalstructureoftrajectoryofsaddle-to-saddlepointsandmultiplelimitcyclearefurtherdiscussedintopologicalstabilitytheory.Thesestructureseasilyproducebifurcationwithperturbation.Theresultssupporttheviewofhydrodynamicinstabilityofvorticesflowfield.

简介：Aquaticvegetationplaysanimportantroleintheflowstructureofopenchannelsandthuschangesthefateandthetransportofsediment.Thisarticleproposesathree-dimensionalturbulencemodelbyintroducingvegetationdensityanddragforceintothecontrolequationsofwaterflowinthepresenceofvegetation.Themodelwasusedtocalculatetheimpactsofsubmergedvegetationontheverticalprofilesoflongitudinalflowvelocities,thechangesofthedepth-averagedflowvelocitiesinacompoundchannelwithemergentvegetationinthefloodplain,theremovalofsuspendedsedimentfromthechannelsbyemergentvegetation,andthebedchangesaroundandinavegetatedisland.Numericalinvestigationsshowthataquaticvegetationretardsflowinthevegetationzone,reducesthesedimenttransportcapacity,andcontributestoerosiononbothsidesofthevegetatedisland.Calculatedresultsagreewellwithexperimentalresults.

简介：InthisarticletheUDFscriptfileintheFluentsoftwarewasrewrittenasthe'connectingfile'fortheFluentandtheANSYS/ABAQUSinorderthatthejoinedfilecanbeusedtodoaero-elasticcomputations.InthiswaythefluidfieldiscomputedbysolvingtheNavier-Stokesequationsandthestructuremovementisintegratedbythedynamicsdirectly.Ananalysisofthecomputedresultsshowsthatthiscoupledmethoddesignedforsimulatingaero-elasticsystemsisworkableandcanbeusedfortheotherfluid-structureinteractionproblems.

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简介：Theeffectofvegetationontheflowstructureandthedispersionina180ocurvedopenchannelisstudied.TheMicroADVisusedtomeasuretheflowvelocitiesbothinthevegetationcasesandthenon-vegetationcase.Itisshownthatthevelocitiesinthevegetationareaaremuchsmallerthanthoseinthenon-vegetationareaandalargevelocitygradientisgeneratedbetweenthevegetationareaandthenon-vegetationarea.ThetransverseandlongitudinaldispersioncoefficientsareanalyzedbasedontheexperimentaldatabyusingthemodifiedN-zonemodels.Itisshownthattheeffectofthevegetationonthetransversedispersioncoefficientissmall,involvingonlychangesofasmallmagnitude,however,sincetheprimaryvelocitiesbecomemuchmoreinhomogeneouswiththepresenceofthevegetation,thelongitudinaldispersioncoefficientsaremuchlargerthanthoseinthenon-vegetationcase.

简介：Thehydrodynamicdamperisadevicetodecreasethemotionofarmamentcarrierbyuseofthewaterresistance.Whenhydrodynamicdamperrushesintothewaterchannelwithhighvelocity,itisacomplicatedflowphenomenonwithfluid-structureinteraction,freesurfaceandmovinginterface.NumericalsimulationusingtheSmoothedParticleHydrodynamics(SPH)methodcoupledwiththeFiniteElement(FE)methodwassuccessfullyconductedtopredictthedynamiccharacteristicsofhydrodynamicdamper.Thewaterresistance,thepressureintheinterfaceandthestressofstructurewereinvestigated,andtherelationshipamongthepeakofwaterresistance,initialvelocityandactualdraughtwasalsodiscussed.Theempiricalformulawasputforwardtopredictthewaterresistance.Anditisfoundthattheresistancecoefficientiscommonlyintherangeof0.3≤C≤0.5,whentheinitialvelocityislargerthan50m/s.ItcanbeseenthattheSPHmethodcoupledwiththeFEmethodhasmanyobviousadvantagesoverothernumericalmethodsforthiscomplicatedflowproblemwithfluid-structureinteraction.

简介：Theproblemofwavepartial/fullreflectionandtransmissionbywave-permeablestructureisapproachedbysolvingtheshape-relatedfunctionwithfocusontheunderstandingofwaveattenuation.2Ddepth-averagedBoussinesqtypewaveequationsaregivenwithnewdampingiteminsimulatingthenonlinearwavetransmissionthroughwave-permeablestructure.1Dwaveequationisexaminedtogivetheanalyticalexpressionoftheabsorbingcoefficient,andiscomparedwithlaboratorydatainflumetocalibratethecoefficients,andtheexpressionisapplieddirectlyinmodifiedBoussinesqtypeequations.Comparedwithwavebasindataforvariousincidentwaveconditions,theaccuratepredictionsofcombineddiffraction-refractioneffectsinsimulatingnonlinearwavegoingthroughwave-permeablebreakwaterintheengineeringapplicationcanbeobtained.Itshowsthatwave-permeablebreakwaterswithproperabsorbingeffectscanbeusedasaneffectivealternativetomassivegravitybreakwatersinreductionofwavetransmissioninshallowwater.

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简介：Existingfarfieldexpressionsofsecondorderpotentialsarebynomeanscomplete.Hencetherehasbeennoexactfarfieldexpressionofsecondorderpotentials.InthispaperthefarfieldexpressionforΦd（2）ispurposelyavoidedindeducingtheformulaeofsecondorderforcesandaseriesoffunctionsΦdRnareused.Thefarfieldexpressionofisgiven,whichfor（x,U,z）∈Σ,φdRn（2）φd（2）.Usingthesepropertiesformulaeforcalculatingsecondorderdiffractionforcesareobtained.Tocalculatetheintegral∫∫1/gfΨdsitisdividedintotwoparts.Oneistheintegraloverafinitedomainandthefunctionundertheintegraliscontinuous,sotheusualapproximateintegrationformulaemaybeused.Theotheristheintegraloveraninfinitedomain.Usingthefarfieldexpressionoffirstorderpotentials,formulaeforcalculatingtheintegraltomeetgivenaccuraciesaregiven.Themooringforceinsurgedirectionisusedforcomparisonbetweennumericalpredictionsandexperimentalmeasurements.Thepredictedresultsarecheckedagainstthemeasuredvalueinaspeciallydesignedtest.Inthelowfrequencydomainofinterest,themooringforcesinsurge,forcalculatedandexperimentalspectraareingoodconsistencysolongasthedampingcoefficientsischoosenappropriately.

简介：TheturbulenceflowFreeSurfacehasimportantapplicationsinhydraulicspillwaysstructure,suchasthehydraulicjump,energydissipationflowetc.Thisisbeingconsideredasverycomplicatedflow,andhasnotyetbeensolvedquitewellbynumericalmethod.Inthispaper,aLarge-scalecomputationalsoftwarepackagearedevelopedfornumericallaboratoryofhydraulicspillwaystructure.Somemethods,suchasturbulencemodel,freesurfaceandirregularboundarytreatingtechniques,scientificcomputervisualizationareputforwardandperformed.

简介：Inthispaper,anoveladaptivemeshσcoordinatemodelisproposedforthestudiesofWaveandStructureInteraction(WSI).Themodelisvalidatedbyusingthecaseofasolitarywavemovementinanopenchannelwithconstantwaterdepthandthecaseofnonbreakingsolitarywavepropagatingoverastep.NumericalresultsagreewellwiththeanalyticalsolutionsobtainedbasedontheBoussinesqtheory,thelaboratorydataandothernumericalmodelresults.Theproposedmodelisthenusedtostudyasolitarywaveinteractingwithasuspendedfixedstructure.

简介：Thecoldflowcharacteristicsareinvestigatedtoshowtheeffectofthestructuralparametersoftheflowguidevaneonthetrappedvortexcombustor(TVC).TheresultsshowthatthestructuralparametershavesignificanteffectsontheTVC.Asa/Hincreases,thetotalpressureloss,thewallshearstressatthebottomofthecavityandtheturbulentintensityinthemaincombustionzoneincrease.b/Bdoesnothaveasignificanteffectonthecavityflowstructureandthetotalpressureloss,andthewallshearstressatthebottomofthecavityincreasesasb/Bincreases.Thereisnosignificantincreaseoftheturbulentintensitywiththeincreaseofb/B.Theincreaseofc/Lhaslittleeffectonthetotalpressureloss,anditisnotconducivetoastablecombustion.Asc/Lincreases,thewallshearstressatthebottomofthecavitydecreases.Whena/H=0.4,b/B=0.4,c/L=0.1,adesirabledual-vortexstructureisformedwithanacceptablepressurelosstoachieveastablecombustion.Moreover,toascertainthattheflameisstablefordifferentvaluesofVmawiththeoptimalstructuralparameters,theeffectofVmaontheflowfieldisdiscussed.Resultssuggestthatthedual-vortexstructurehasnorelationshipwiththeincreaseofVma.Furthermore,anunsteadysimulationisconductedtoshowthegenerationandthedevelopmentofthedual-vortex.

简介：ANonlinearFluidDamping(NFD)intheformofthesquare-velocityisappliedintheresponseanalysisofVortex-InducedVibrations(VIV).Itsnonlinearhydrodynamiceffectsonthecoupledwakeandstructureoscillatorsareinvestigated.AcomparisonbetweenthecoupledsystemswiththelinearandnonlinearfluiddampingsandexperimentsshowsthattheNFDmodelcanwelldescriberesponsecharacteristics,suchastheamplificationofbodydisplacementatlock-inandfrequencylock-in,bothathighandlowmassratios.Particularly,thepredictedpeakamplitudeofthebodyintheGriffinplotisingoodagreementwithexperimentaldataandempiricalequation,indicatingthesignificanteffectoftheNFDonthestructuremotion.

简介：Thecochleaisanimportantstructureinthehearingsystemofhumanity.Itsuniquestructureenablesthesensibilitytothesoundwavesofvariedfrequencies.ThewidelyacceptedmodelofthecochleaisexpressedasalongtubelongitudinallydividedbyamembranenamedtheBasilarMembrane(BM),intotwofluid-filledchannels.Basedonvariousassumptionsforthecochlearfluidandstructure,simplifiedmathematicalandmechanicalcochlearmodelsweredevelopedtohelptounderstandthemechanismofthecomplexcoupledsysteminthepastdecades.ThispaperproposesahydrodynamicnumericalcochlearmodelwithconsiderationoftheFluid-StructureInteraction(FSI).Inthismodel,thecochlearlymphisconsideredasinaNewtonianviscousfluid,andthebasilarmembraneismodeledasacompositestructure.Thetravelingwaveissimulated.Alsofocusingonthepressureinthefluidfield,theresultsarecomparedwithstudiesofPetersonandBogert,whereitwasassumedthattheslowcompressivewavesaretravelingalongtheBM.Furthermore,thetransmittingtimeofthecochleartravelingwaveisalsodiscussed.

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