简介：TheWorld'sfirstcommercialwavepowerstationhassuccessfullyfedelectricityintotheUK'snationalgridontheScottishislandofIslay.Thestationhassecureda15yearpowerpurchaseagreementwiththemjorpublicelectricitysuppliersinScotland.

简介：Inrealseastates,damageincidentsonoffshorefloatingstructuresarenotduetothewholetimeseriesofwaveelevationcharacterizedasstatisticalonebutduetofewextremewavesorwavegroupsinirregularwavetrain.So,usingCFDtoolstopreciselysimulatepredeterminedirregularwavetrainwilllaysoundbasisforunderstandingthelocalcharacteristicoftheflowfieldandimpactloadsonoffshorefloatingstructureswhendamageincidentsoccur.Inthisarticle,thegenerationofsingleextremewaveisinvestigatedinanumericalwavetank.First,experimentalirregularwavetrainisdecomposedintocertainnumberofsmall-amplitudewaves.TheFourierseriesexpansionisperformedtodeterminetheamplitudeandinitialphaseangleofeachwavecomponent.Ahydrodynamictransferfunctionisusedtocalculatetheamplitudeofwave-makermotionassociatedwitheachwavecomponent.Thensuperpositioniscarriedoutonallofthewave-makermotioncomponentstogetthefinalwave-makermotion.Withthewave-makermotionasinput,simulationofthesingleextremeirregularwavetrainismodeledsuccessfully.Thenthemethodisappliedtosimulatingamuchmorecomplicatedirregularwavetrain.OnceagainmainfeaturesofthecomplicatedirregularwavetrainarereproducedcomparedwithexperimentcarriedoutinthenewdeepwaterexperimentalbasinatShanghaiJiaoTongUniversity.Inthesimulation,dynamicmeshmethodisenabledtomodelthepiston-typewave-maker,theVolumeOfFluid(VOF)methodisemployedtocapturethefreesurfaceandadissipationzoneisintroducedtodealwithwavereflection.

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

简介：Uptonow,therearenosatisfactorynumericalmethodsforsimulatingwaveresistanceoftrimarans,mainlyduetothedifficultyrelatedwiththestrongnonlinearfeaturesofthepiecehullwavemakingandtheirinterference.Thisarticleproposesanumericalmethodforquickandeffectivecalculationofwaveresistanceoftrimaranstobeusedinengineeringapplications.BasedonWyatt'swork,thenonlinearfreesurfaceboundarycondition,thetimedomainconcept,andthefullnonlinearwavemakingtheory,usingtheRankinesourceGreenfunction,the3-Dsurfacepanelmethodisexpandedtosolvethetrimaranwavemakingproblems,withhighordernonlinearfactorsbeingtakenintoaccount,suchastheinfluenceofthesinkingandtrim,transom,andshipwaveimmersedhullsurface.Andthesoftwareissuccessfullydevelopedtoimplementthemethod,whichisvalidated.Severaltrimaranmodels,includingapracticaltrimaranwithasonardomeandthetransom,areusedasnumericalcalculationsamples,theirwavemakingresistanceiscalculatedbothbythepresentmethodandsomeothermethodssuchaslinear(Dawson)methods.Moreover,samplemodelresistancetestswerecarriedouttoprovidedataforcomparison,validationandanalysis.Throughthevalidationbymodelexperiments,itisconcludedthatpresentmethodcanwellpredictthewavemakingresistance,sinkingandtrim,andtheaccuracyofwavemakingresistancecalculationissignificantlyimprovedbytakingthetrimandsinkingintoaccount,especiallyathighspeeds.

简介：Atheoreticalapproachisderivedtostudyinteractionoflinearwaterwaveswithanairbubblecurtainusedasapneumaticbreakwater.Modellingofwavetransmissionthroughanaerialbarrierisacomplextaskduetoaneedtocoverprocessesassociatedwithwave-currentinteraction,effectsoftwo-phaseflows,wavedamping,etc..Aninitialboundary-valueproblemissolvedbyapplyinganefficienteigenfunctionexpansionmethodandatime-steppingprocedure.Thederivedsemi-analyticalsolutionisusedtostudytheeffectofbasicparametersofthemodelonwavedissipativepropertiesofthepneumaticbreakwater.Resultsshowthatwavedampingbythebreakwaterismainlyaffectedbyanairflowrate.Theincreasedairdischargeresultsinhighervelocitiesofascendingbubblesandincreasesaerialbarrierwidth.Thisleadstoasubstantialreductionoftransmittedwaveheights,especiallyforwavesofintermediatelengthandshortwaves.Inordertoverifytheapplicabilityofthepresentedtheoreticalapproach,laboratoryexperimentsareconductedinawaveflumefordifferentwaveregimesandpneumaticbreakwatercharacteristics.Theanalysisofawavetransmissioncoefficientcalculatednumericallyandmeasuredinthelaboratoryconfirmsthatthederivedmodelcanbeusedforacertainrangeofwaveconditions.

简介：Throughaseriesofmodeltests,thewaveforcesonhorizontalandinclinedcircularcylindersaremeasuredandanalyzed.BasedonMorisonEquationandStokessecondorderwavetheory,therelationshipbetweenthehydrodynamicforcecoefficientswithKCnumberandsub-mergedwaterdepthaswellforhorizontalcylindersareanalyzed,alsotherelationshipbetweenthehydrodynamicforcecoefficientswithKCnumber,inclinedangleandtheeffectofwaterfreesurfaceaswellfortheinclinedcylindersareinvestigated.

简介：Anumericalmodelisproposedforthesimulationofimpulsewavesgeneratedbylandslides.Thefluid-likelandslideismodeledasageneralizednon-Newtonianvisco-plasticfluid.Theconservativelevelsetmethodisextendedtothen-phaseflowandappliedtocapturetheinterfacesofair,waterandlandslide.Numericalresultsshowanexcellentperformanceofthecurrentmodeltocapturethewholeprocessofthelandslideandtheimpulsewavegeneration.

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

简介：NumericalsimulationsofextremewavegenerationarecarriedoutbyusingtheVolumeOfFluid(VOF)method.Extremewavesaregeneratedbasedonwavefocusingina2-Dnumericalmodel.TovalidatethecapabilityoftheVOF-basedmodeldescribedinthisarticle,thepropagationofregularwavesiscomputedandcomparedwiththetheoreticalresults.Byadjustingthephasesofwavecomponents,extremewavesareformedatgiventimeandgivenpositioninthecomputation.Thenumericalresultsarecomparedwiththeoreticalsolutionsandexperimentaldata.ItisconcludedthatthepresentmodelbasedontheVOFtechniquecanprovideacceptablyaccuratenumericalresultstoservepracticalpurposes.

简介：ThepresentworkadoptstheCOHERENS-SWANmodeldevelopedbythefirstauthorthroughcouplingthree-dimensionalhydrodynamicmodel(COHERENS)andthird-generationwavemodel(SWAN).InsidetheCOHERENS-SWAN,theSWANisregardedasasubroutineandthetime-andspace-varyingcurrentvelocityandsurfaceelevationareobtainedfromtheCOHERENS.Wave-enhancedbottomshearstress,waveinducedsurfacemixinglengthandwavedependentsurfacedragcoefficienthavebeenintroducedintotheCOHERENS.Secondly,aswave-enhancedbottomshearstress('bottomshearstress'describedasBSSsometimesinthisarticle)isconcerned,amodifiedbottomshearstressGrantandMadsenmodelwhichintroducesrandomwavefieldisgivenandintroducedtoCOHERENS-SWAN.COHERENS-SWANisalsoadoptedtosimulatethree-dimensionalflowintheYellowRiverDeltawithwave-currentco-existing.Fournumericalexperimentsweregiventostudytheeffectsofwave-currentinteractiononenhancingbottomshearstress.Thesimulatedcurrentvelocities,waveheightandwaveperiodmatchwellwithfieldmeasurementdata.Thesimulatedsignificantwaveheightandwaveperiodforthecasewithconsideringtheeffectsofcurrentcangivebetteragreementwithmeasurementdatathanthecasewithoutinvolvingtheeffectsofcurrent.Theintroductionofrandomwavegenerateslowerthebottomshearstressthanthecasewithoutintroducingit.Thereareobviousdifferencesbetweenbottomshearstressoftwowayinteractionandonewayinteraction.VelocityfieldobtainedbytheCOHERENS-SWANisreasonableaccordingtopreviousstudiesandmeasurements.

简介：Convectioninahorizontalfluidlayerheatedfrombelowisoneofmodelsforstudyingpatternsofconvectioninbinaryfluidmixturesandhasbeenextensivelystudied.Inthisarticle,theconvectionstructuresinarectangularcellwereinvestigatedfortheaspect-ratioΓ=12andtheseparationratioψ=-0.47.SimulationswerepreformedbysolvingthehydrodynamicequationsusingtheSIMPLEmethod.ACounterPropagatingWave(CPW)statewasfoundinbinaryfluidconvectionwithaperiodicallyhorizontalmotionofdefects,andthepatterndynamicswasfurtherdiscuss.

简介：ATime-domainHigher-OrderBoundaryElementMethod(THOBEM)isdevelopedforsimulatingwave-currentinteractionswith3-Dfloatingbodies.ThroughaTaylorseriesexpansionandaperturbationprocedure,themodelisformulatedtothefirst-orderinthewavesteepnessandinthecurrentvelocity,respectively.Theboundaryvalueproblemisdecomposedintoasteadydouble-bodyflowproblemandanunsteadywaveproblem.Higher-orderboundaryintegralequationmethodsarethenusedtosolvetheproposedproblemswithafourth-orderRunge-Kuttamethodforthetimemarching.Anartificialdampinglayerisadoptedtodissipatethescatteringwaves.Differentfromtheothertime-domainnumericalmodels,whichareoftenfocusedonthewave-currentinteractionwithrestrainedbodies,thepresentmodeldealswithafloatinghemisphere.Thenumericalresultsofwaveforces,waverun-upandbodyresponseareallinacloseagreementwiththoseobtainedbyfrequency-domainmethods.Theproposednumericalmodelisfurtherappliedtoinvestigatewave-currentinteractionswithafloatingbodyofcomplicatedgeometry.Inthiswork,theregularandfocusedwavecombinedwithcurrentinteractingwithatruss-sparplatformisinvestigated.

简介：BasedonGreen’stheorem,atimedomainnumericalmodelwasconstructedtosimulatewavemakingphenomenoncausedbyamovingship.Inthisarticle,theRankinesourcesanddipoleswereplacedonboundarysurfaces(i.e.,theshipsurfaceandfreesurface),andatime-steppingschemewasemployed.Itsuniquecharacteristicisthatsteadystatecanberealizedfrominitialvaluebyemployingthetime-steppingschemeandunsteadyfreesurfaceconditions.Intimedomain,iftheresultsofunsteadyflowproblemtendtodatastabilizationaftermanytimestepsofcomputation,theycouldberegardedasthedataofsteadyones.Thismodelcouldbeemployedtosteadyorunsteadyproblems.Theoreticalreasoningandcomputationalprocessofthismethodwasdescribedindetail.Thelinearandnonlinearboundaryconditionsonbodysurfacewerestudied,andtherelativemeanstorealizetheseboundaryconditionsiniterativecomputationwerealsodiscussed.SomeproperparametersaboutthemodeloftheWigleyhullweredeterminedbymanynumericaltests,andtheirinfluencesonwavemakingresistanceandwavepatternwerediscussed.Accordingtothecomparisonbetweennumericalresultsanddataavailableinrelativereferences,themethodusedinthisworkisproventobeareliablemethodintimedomain.Andthelatticereorganizationineverytimestepcomputationisafeasiblenumericalapproach.

简介：Theshiphullsurfaceoptimizationbasedonthewaveresistanceisanimportantissueintheshipengineeringindustry.Thewaveletmethodmayprovideaconvenienttoolforthesurfacehulloptimization.Asapreliminarystudy,weusethewaveletmethodtooptimizethehullsurfacebasedontheMichelwaveresistanceforaWigleymodelinthispaper.Firstly,weexpressthemodel’ssurfacebythewaveletdecompositionexpressionsandobtainareconstructedsurfaceandthenvalidateitsaccuracy.Secondly,werewritetheMichelwaveresistanceformulainthewaveletbases,resultinginasimpleformulacontainingonlytheshiphullsurface’swaveletcoefficients.Thirdly,wetakethesewaveletcoefficientsasoptimizationvariables,andanalyzethemainwaveresistancedistributionintermsofscalesandlocations,toreducethenumberofoptimizationvariables.Finally,weobtaintheoptimalhullsurfaceoftheWigleymodelthroughgeneticalgorithms,reducingthewaveresistancealmostbyahalf.Itisshownthatthewaveletmethodmayprovideanewapproachforthehulloptimization.

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简介：Thisarticleanalyzestheverticalstructureoftheonshorecurrentincludingthewave-inducedcurrentbyanequationdevelopedfortheradiationstressagainstwaterdepth.AcoupledmodelCOHERENS-SEDisadoptedtocalculatethewave,tidalcurrent,wave-inducedcurrentandsedimentsimultaneously.ByapplyingthenewmodeltoYangpuBay,itsreliabilityisverified.Thenanidealcoastaldomainisdefinedtosimulatethenearshorecurrentandwavesetupwithnormalincidentwaves.Thenumericalandexperimentalresultsfortheverticalstructureshowtwoundertows,alsoavisiblesetupinthesurfzone.Itdemonstratestheimportanceoftheradiationstressinwave-inducedcurrentsandmeanwaterlevels(set-up/down).

简介：NumercialsimulationofseasurfacedirectionalwavespectraundertyphoonwindforcingintheSouthChinaSea(SCS)wascarreidoutusingtheWAVEWATCH-IIIwavemodel.Thesimulationwasrunfor210huntiltheTyphoonDamrey(2005)approachedVietnam.Thesimulateddatawerecomparedwithbuoyobservations,whichwereobtainedinthenorthwestseaareaofHainanIsland.Theresultsshowthatthesignificantwaveheight,wavedirection,wavelengthandfrequencyspetraagreewellwithbuoyobservations.Thespatialcharacteristicsofthesignifciantwaveheight,meanwaveperiod,meanwavelength,waveageanddirectionalspectradependontherelativepositionfromthetyphooncenter.Also,themisalignmentbetweenlocalwindandwavedirectionswereinvestigated.

简介：Atime-domainKelvinsourcehigh-orderpanelmethodbasedonNURBSisdevelopedandappliedtosolvetheunsteadywave-makingproblems.Numericalresultsofinstantwaveresistanceandfreesurfaceelevationarepresentedandcomparedwiththeavailabyresultsbyotherauthors,forsubmergedspheroidandspherebeneaththefreesurfaceandforsurfaceshipofWigleymodelsmovingwithunsteadyspeed.Theagreementissatisfying.

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