简介：-Waverefraction-diffractionduetoalargeoceanstructureandtopographyinthepresenceofa’currentarestudiednumerically.Themathematicalmodelisthemild-slopeequationdevelopedbyKirby(1984).Thisequationissolvedusingafiniteandboundaryelementmethod.Thephysicaldomainisdevid-edintotworegions:aslowlyvaryingtopographyregionandaconstantwaterdepthregion.Forwavespropagatingintheconstantwaterdepthregion,withoutcurrentinterfering,themild-slopeequationisthenreducedtotheHelmholtzequationwhichissolvedbyboundaryelementmethod.Invaryingtopographyregion,thisequationwillbesolvedbyfiniteelementmethod.Conservationofmassandenergyfluxofthefluidbetweenthesetworegionsisrequiredforcompositionofthesetwonumericalmethods.Thenumericalschemeproposedhereiscapableofdealingwithwaterwaveproblemsofdifferentwaterdepthswiththemaincharactersofthesetwomethods.

简介：-Thispaperpresentsacalculationmethodforthediffractionofbothregularwavesandirregularwavesofthesingledirectionalfrequencyspectrumbehindasinglejettywithatheoreticalanalysis,whichhasbeenconfirmedthroughthemodelexperiments,derivesamethodofcomputingthediffractedirregularwavesbehindthesinglejettywiththetheoreticalanalysisonthebasisofcomputationofthefielddataandgivestheformulasandthefiguresofthecomputationofwavediffractionsbehindtheverticalwallormoundsinglejetties.

简介：Thecoefficientofdeffractionofregularwavesbehindthedoublejettyhasbeencomputedinthispaperatfirstbyusingthesingularitydistributionmethod.Themodeltestsconductedfordiffractionofirregularwaveswithaunidirectionalfrequencyspectrumhaveconfirmedgoodagreementbetweenthedatameasuredinexperimentsandtheresultscomputedbythesingularitydistributionmethodplusthelinearsuperpositionmethodfortheenergyofcomponentwavesinthedirectionalfrequencyspectra.Therefore,thistechniqueforcomponentwavesinthedirectionalspectrahasbeenfurtherusedtocomputediffractionofirregularwavesofmultidirection,includingtheemploymentofadirectionaldistributionfunctionofthecos2type,aswellastheBretschneider-Misuyannfrequencyspectrum.

简介：Twodifferentmethodsforincorporatingdiffractioneffectintowaveactionbalanceequationbasedcoastalspectralwavemodels,WABEDandSWAN,arediscussedandevaluatedwithrespecttotheirformulations,numericalimplementations,andmodelingcapabilities.Bothmodelswereruntosimulatethewavetransformationthroughagapbetweentwoinfinitelylongbreakwatersandthatacrossanellipticalshoalobservedinlaboratorystudies,withtheemphasislaidonthediffractioninducedbyeitherobstaclesorwaveamplitudevariations.CalculationsofWABEDwerecomparedwithSommerfeld'sanalyticalsolutions,experimentalobservationsandSWANsimulations.Itisshownthatbothmethodscanpredictreasonablywavediffractionforthetwocasesstudiedherein,andafairlybetterperformanceisprovidedbyWABEDforstrongerdiffractioncase.

简介：-Forthediscretizationofhigherorderelements,thispaperpresentsamodifiedintegraldomainmethodtoremovetheirregularfrequenciesinheritedintheintegralequationofwavediffractionandradiationfromasurface-piercingbody.Thesetofover-determinedlinearequationsobtainedfromthemethodismodifiedintoanormalsetoflinearequationsbysuperposingasetoflinearequationswithzerosolutions.Numericalexperimentshavealsobeencarriedouttofindtheoptimumchoiceofthesizeoftheauxiliarydomainandthediscretizationonit.

简介：-Amild-slopeequationforcombinedrefractionanddiffractionofrandomwavesintheindependenttimecurrentisderivedusingKirbyequation(1984).Inthederivation,thefrequencyofrandomwavesisrepresentedbasedonthetimeseriesconcept,byatypicalfrequencyanditsdeviationpart.Numericalresults,comparedwiththoseoflaboratoryexperiments,demonstratethatnewsetofirregularmildslopeequationwithcurrentisofgoodadaptability.

简介：Ahigher-orderboundaryelementmethod(HOBEM)forsimulatingthefullynonlinearregularwavepropagationanddiffractionaroundafixedverticalcircularcylinderisinvestigated.Thedomaindecompositionmethodwithcontinuityconditionsenforcedontheinterfacesbetweentheadjacentsub-domainsisimplementedforreducingthecomputationalcost.Byadjustingthealgorithmofiterativeprocedureontheinterfaces,fourtypesofcouplingstrategiesareestablished,thatis,Dirchlet/Dirchlet-Neumman/Neumman(D/D-N/N),Dirchlet-Neumman(D-N),Neumman-Dirchlet(N-D)andMixedDirchlet-Neumman/Neumman-Dirchlet(MixedD-N/N-D).Numericalsimulationsindicatethatthedomaindecompositionmethodscanprovideaccurateresultscomparedwiththatofthesingledomainmethod.Accordingtothecomparisonsofcomputationalefficiency,theD/D-N/Ncouplingstrategyisrecommendedforthewavepropagationproblem.Asforthewave-bodyinteractionproblem,theMixedD-N/N-Dcouplingstrategycanobtainthehighestcomputationalefficiency.

简介：Inthispaper,theprincipleofmirrorimageisusedtotransformtheproblemofwavediffractionfromacircularcylinderinfrontoforthogonalverticalwallsintotheproblemofdiffractionoffoursymmetricincidentwavesfromfoursymmetricallyarrangedcircularcylinders,andthentheeigenfunctionexpansionofvelocitypotentialandGrafsadditiontheoremareusedtogivetheanalyticalsolutiontothewavediffractionproblem.Therelationofthetotalwaveforceoncylindertothedistancebetweenthecylinderandorthogonalverticalwallsandtheincidenceangleofwaveisalsostudiedbynumericalcomputation.

简介：-Inthispaper,ananalyticalsolutionintheouterregionoffinitewaterdepthisderivedforthesecond-orderdiffractionpotential,whichgivesaclearphysicalmeaningofthewavetransmissionandreflectioncharacteristicsinthefarfield.Anumericalmethod-simpleGreen’sfunctiontechnique-forcalculatingthesecond-orderdiffractionpotentialintheinnerregionisalsodescribed.Numericalresultsareprovidedforthesecond-orderwaveforcesonasemi-submergedcylinder.Itisfoundthatthecontributionofsecond-orderdiffractionpotentialtosecond-orderwaveforcesisimportant.Theeffectofwaterdepthandsubmergeddepthonthewaveforceisalsodiscussed.

简介：Atime-domainmethodisappliedtosimulatenonlinearwavediffractionaroundasurfacepiercing3-Darbitrarybody.ThemethodinvolvestheapplicationofTaylorseriesexpansionsandtheuseofperturbationproceduretoestablishthecorrespondingboundaryvalueproblemswithrespecttoatime-independentfluiddomain.AboundaryelementmethodbasedonB-splineexpansionisusedtocalculatethewavefieldateachtimestep,andthefreesurfaceboundaryconditionissatisfiedtothesecondorderofwavesteepnessbyanumericalintegrationintime.Anartificialdampinglayerisadoptedonthefreesurfacefortheremovalofwavereflectionfromtheouterboundary.Asanillustration,themethodisusedtocomputethesecond-orderwaveforcesandrun-uponasurface-piercingcircularcylinder.Thepresentmethodisfoundtobeaccurate,computationallyefficient,andnumericallystable.