简介：Thequasi-2Dmodel,takingintoaccounttheaxialvelocityprofileinthecrosssectionandneglectingtheconvectiveterminthe2-Dequation,canmoreaccuratelysimulatethewaterhammerthanthe1-Dmodelusingthecross-sectionalmeanvelocity.However,ascomparedwiththe1-Dmodel,thequasi-2Dmodelbearsahighercomputationalburden.Inordertoimprovethecomputationalefficiency,the1-Dmethodisproposedtobeusedtosolvedirectlythepressureheadandthedischargeinthequasi-2Dmodelinthispaper,basedonthefactthatthepressureheadobtainedasthesolutionofthetwo-dimensionalcharacteristicequationisidenticaltothatsolvedbythe1-Dcharacteristicequations.Theproposedschemesolvesdirectlythe1-DcharacteristicequationsforthepressureheadandthedischargeusingtheMOCandsolvesthe2-Dcharacteristicequationfortheaxialvelocitiesinordertocalculatethewallshearstress.Iftheradialvelocityisneeded,itcanbeevaluatedeasilybyanexplicitequationderivedfromtheexplicit2-Dcharacteristicequation.Inthenumericaltest,theaccuracyandtheefficiencyoftheproposedschemearecomparedwithtwoexistingquasi-two-dimensionalmodelsusingtheMOC.Itisshownthattheproposedschemehasthesameaccuracyasthetwoquasi-2Dmodels,butrequireslesscomputationaltime.Therefore,itisefficienttousetheproposedschemetosimulatethe2-Dwaterhammerflows.

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.