摘要：本文为ANSYSAQWA-WAVEVersion12官方用户手册，聚焦波浪载荷向有限元模型传递的核心功能。手册系统阐述水动力绕射/辐射力、莫里森方程惯性与拖曳力、流耦合的理论基础，详细说明输入文件格式、结构与水动力模型对接、工况定义、坐标系转换、单位换算及载荷映射流程。支持管单元、梁单元、壳/实体单元载荷分配，提供固定/浮式结构、对称模型、环形与杆件载荷赋值方法，兼容中性文件接口，可对接ASAS与ANSYS。文档含命令说明、算例与旧版格式对照，为海洋平台、船舶等结构的波浪载荷施加提供完整操作指南。AQWA-WAVEUserManualHydrodynamicLoadTransferVersion12April2009CenturyDynamicsLimitedSuite1,3HorshamGatesNorthStreetHorshamWestSussexRH135PJENGLANDTelephone+44(0)1403270066Fax+44(0)1403270099Emailsupport-uk@ansys.comURLwww.ansys.com/customerportalCopyright2009.CenturyDynamicsLimited.AllRightsReserved.CenturyDynamicsisasubsidiaryofANSYS,Inc.Unauthoriseduse,distributionorduplicationisprohibitedRevisionInformationTheinformationinthisguideappliestoallANSYS,Inc.productsreleasedonorafterthisdate,untilsupersededbyanewerversionofthisguide.Thisguidereplacesindividualproductinstallationguidesfrompreviousreleases.CopyrightandTrademarkInformationANSYS,ANSYSWorkbench,CFX,AUTODYN,ASAS,AQWAandanyandallANSYS,Inc.productandservicenamesareregisteredtrademarksortrademarksofANSYS,Inc.oritssubsidiarieslocatedintheUnitedStatesorothercountries.ICEMCFDisatrademarklicensedbyANSYS,Inc.ABAQUSisaregisteredtrademarkofABAQUS,IncAdobeandAcrobatareregisteredtrademarksofAdobeSystemsIncorporatedCompaqisaregisteredtrademarkofCompaqComputerCorporationDelphiisaregisteredtrademarkofBorlandSoftwareCorporationDXFisatrademarkofAutodesk,IncFEMGV,FEMGENandFEMVIEWaretrademarksofFemsysLimitedFLEXlmandFLEXnetareregisteredtrademarksofMacrovisionCorporationFormulaOneisatrademarkofVisualComponents,IncGINOisaregisteredtrademarkofBradlyAssociatesLtdIGESisatrademarkofIGESDataAnalysis,IncIntelisaregisteredtrademarkofIntelCorporationMathcadisaregisteredtrademarkofMathsoftEngineering&Education,Inc.Microsoft,Windows,Windows2000,WindowsXPandExcelareregisteredtrademarksofMicrosoftCorporationNASTRANisaregisteredtrademarkoftheNationalAeronauticsandSpaceAdministration.PATRANisaregisteredtrademarkofMSCSoftwareCorporationSentinelSuperPro™isatrademarkofRainbowTechnologies,IncSESAMisaregisteredtrademarkofDNVSoftwareSoftlokisatrademarkofSoftlokInternationalLtdAllothertrademarksorregisteredtrademarksarethepropertyoftheirrespectiveowners.DisclaimerNoticeTHISANSYSSOFTWAREPRODUCTANDPROGRAMDOCUMENTATIONINCLUDETRADESECRETSANDARECONFIDENTIALANDPROPRIETARYPRODUCTSOFANSYS,INC.,ITSSUBSIDIARIES,ORLICENSORS.ThesoftwareproductsanddocumentationarefurnishedbyANSYS,Inc.,itssubsidiaries,oraffiliatesunderasoftwarelicenseagreementthatcontainsprovisionsconcerningnon-disclosure,copying,lengthandnatureofuse,compliancewithexportinglaws,warranties,disclaimers,limitationsofliability,andremedies,andotherprovisions.Thesoftwareproductsanddocumentationmaybeused,disclosed,transferred,orcopiedonlyinaccordancewiththetermsandconditionsofthatsoftwarelicenseagreement.ANSYS,Inc.andANSYSEurope,Ltd.areULregisteredISO9001:2000Companies.U.S.GovernmentRightsForU.S.Governmentusers,exceptasspecificallygrantedbytheANSYS,Inc.softwarelicenseagreement,theuse,duplication,ordisclosurebytheUnitedStatesGovernmentissubjecttorestrictionsstatedintheANSYS,Inc.softwarelicenseagreementandFAR12.212(fornon-DODlicenses).Third-PartySoftwareTheproductsdescribedinthisdocumentcontainthefollowinglicensedsoftwarethatrequiresreproductionofthefollowingnotices.Copyright1984-1989,1994AdobeSystemsIncorporated.Copyright1988,1994DigitalEquipmentCorporation.Permissiontouse,copy,modify,distributeandsellthissoftwareanditsdocumentationforanypurposeandwithoutfeeisherebygranted,providedthattheabovecopyrightnoticesappearinallcopiesandthatboththosecopyrightnoticesandthispermissionnoticeappearinsupportingdocumentation,andthatthenamesofAdobeSystemsandDigitalEquipmentCorporationnotbeusedinadvertisingorpublicitypertainingtodistributionofthesoftwarewithoutspecific,writtenpriorpermission.AdobeSystems&DigitalEquipmentCorporationmakenorepresentationsaboutthesuitabilityofthissoftwareforanypurpose.Itisprovided"asis"withoutexpressorimpliedwarranty.AdvancedVisualSystemsAllrightsreserved.UseofthissoftwareissubjecttothetermsoftheagreementwithAdvancedVisualSystemsInc.oritsdistributorsandlicensee.Use,duplicationordisclosurebytheFederalGovernmentissubjecttotherestrictionssetforthinFAR52.227-19(c),CommercialComputerSoftwareor,forDepartmentofDefenseusers,byDFAR252.227-7202.3.FormulaOneisatrademarkofVisualComponents,Inc.TheproductcontainsFormulaOnefromVisualComponents,Inc.Copyright1994-1995.Allrightsreserved.Microsoft,Windows,Windows2000andWindowsXPareregisteredtrademarksofMicrosoftCorporationwhirlgifCopyright(c)1997,1998,1999byHansDinsen-HansenCopyright(c)1995,1996byKevinKadowCopyright(c)1990,1991,1992byMarkPodlipec.Allrightsreserved.Thissoftwaremaybefreelycopied,modifiedandredistributedwithoutfeeprovidedthatthiscopyrightnoticeispreservedintactonallcopiesandmodifiedcopies.Thereisnowarrantyorotherguaranteeoffitnessofthissoftware.Itisprovidedsolely"asis".Theauthor(s)disclaim(s)allresponsibilityandliabilitywithrespecttothissoftware'susageoritseffectuponhardwareorcomputersystems.TheGraphicsInterchangeformat(c)istheCopyrightpropertyofCompuserveIncorporated.Gif(sm)isaServiceMarkpropertyofCompuserveIncorporated.TheANSYSthird-partysoftwareinformationisalsoavailableviadownloadfromtheCustomerPortalontheANSYSwebpage.Ifyouareunabletoaccessthethird-partylegalnotices,pleasecontactANSYS,Inc.PublishedintheUnitedKingdomAQWAWAVEUserManualUpdateSheetforVersion12AQWAWAVEUserManualVersion1210February2009Modifications:Thefollowingmodificationshavebeenincorporated:1.INTRODUCTION1.1OverviewAQWA-WAVEformspartoftheASAS™andAQWA™suitesofprogramsdevelopedbyCenturyDynamicsLimited.Itsfunctionistotransferwaveloadsonfixedorfloatingstructures(calculatedbytheradiation/diffractionprogram,AQWA-LINE)toafiniteelement,structuralanalysispackage.AQWA-WAVEformsalinkbetweentheAQWAandASASsuitesofprograms.ItcanalsooutputwaveloadstotheANSYS®system.AQWA-WAVEalsohastheabilitytoreadinstructuralandhydrodynamicdatadefinedinneutralformatandoutputthewaveloadsinneutralformat.ThisfacilitypermitstheprogramtointerfacewitharangeofhydrodynamicandFEprograms.AQWA-LINEusesameshcomposedofpanels,orfacets,tomodelthestructure.Itcalculatespressuresatthefacetcentroids,duetotheincident,diffractedandradiatedwaves,forarangeofwaveperiodsanddirectionsspecifiedbytheuser.ThepressurescalculatedbyAQWA-LINEeffectivelyrelatetowavesofunitamplitude.ThesepressuresthereforehavetobescaledbyAQWA-WAVEtorelatetotheactualwaveheightrequiredbytheAQWA-WAVEuser.AQWA-WAVEcanbeusedtotransferfacetloadstooneoftwotypesofstructuralmodel:•asimplified,normallysinglecomponent,stickmodel,inwhichonlytubeorbeamelementsaresubjecttohydrodynamicloads•asingleormulti-componentmodel,inwhichhydrodynamicloadsactmainlyuponthewettedsurfacesofshellorbrickelements.Inthecaseofbrickelements,aspecialloadcaseisrequiredintheASASmastercomponentfile,toidentifywhichfacesofthebrickarewetted.AsAQWA-LINEuseslinearwavetheory,itcannotcalculatedragforces.ProvisionisthereforemadeforAQWA-WAVEtocalculatethedragforces,includingtheeffectofcurrent.TheprogramalsoallowsforbothdragandinertialforcestobecalculatedforadditionalstructuralelementsintheFEmodel,whicharetoosmalltobemodelledusingAQWA-LINEfacets.AQWA-WAVEevaluatesallforcesataparticularphaseinthewavecycle.Theusercanrequestmanywavecases(specifiedbywaveperiod,wavedirection,waveheight,wavephaseandcurrentprofile)inasinglerunoftheprogram.WhenAQWA-WAVEisexecuted,theprogramreadsacompletesetofFEinputdatafilesandwritesoutanewsetwithallthenecessaryloadcasesinserted.Forfloatingstructures,balancingaccelerationsarealsowrittenintotheoutputFEfiles.Therearecurrentlyanumberofprogramlimitations,whichshouldbenotedbytheuser:•AQWA-WAVEdoesnotcurrentlyrecogniseeitherOFFSETSorLOCALAXESdefinedfortubeorbeamelementsintheASASgeometry(GEOM)deck.Theusermustnotthereforedefinesuchitemsinthisdeck.•WhensettingupanASASmodelusingSHELLtypeelements,theusermustensurethattheinputorderofthenodesisanti-clockwise,whenviewingthewettedsurfaceoftheelement(thesameconventionasinAQWA-LINE).1.2ManualLayoutSection2discussesthetheoreticalbasisoftheAQWA-WAVEprogram.Section3givesadetailedexplanationoftheAQWA-WAVEdataformatfromVersion14.03.Section4givesinformationonhowtoruntheprogram.Section5providesanexampleofprogramuse.AppendixAgivesadetailedexplanationoftheAQWA-WAVEdataformatuptoVersion14.02.AppendixBgivesadetailedexplanationoftheAQWA-WAVEneutralfileformats.2.THEORY2.1ProgramStructuresAQWA-WAVEiscurrentlyrunasapost-processortoAQWA-LINEtotransferthefacetpressuresfromAQWA™toastructuralmodelcreatedusingASAS™data.Optionally,dragandinertialoadsontubularcomponentsofthestructuremaybecalculatedandaddedtothediffraction/radiationforcesfromAQWA-LINE.TheASASmodelmaycomprise1Dor3Delements.Typical1Delementsaretubesandbeams.TheelementsthatmaybeloadedbyAQWA-WAVEare:TUBEBEAMBM3DGroupsofAQWAfacetsmaybeassociatedwitheachtubeornodeintheASASmodelanddiffraction/radiationforcesassignedaccordingly.(Theusershoulddecidehowthefacetloadsaretobedistributed,beforerunningAQWA-LINE,sothatappropriateelementgroupingscanbesetupinthatrun.)DragandinertialoadsonthetubescanalsobecalculatedandaddedtotheseforcesusingMorison’sequation.3Dstructurescomprisesolidorshellelements.TheelementsthatmaybeloadedbyAQWA-WAVEare:Diffractionradiationforcesareonceagaintransferredtotheseelements,thistimebyinterpolationoffacetpressurestothewettedexternalsurfaceoftheelements.Dragforcesonthesamesurfacescanbecalculatedbytheprogramandagainassignedaspressurestotheelements.TheASASmodelmaybesubdividedintocomponents.AQWA-WAVEcanloadthesecomponentsaccordingtotheirpositioninthefinalassembledmodel.LoadassemblydatawillbeproducedthatwillallowtheASASrunstoproceedwithnofurtherdataediting.Figure2-1showsthedataflowandprogramstructureforatypicalanalysisusingAQWA-LINEandAQWA-WAVE.Ascanbeseen,theAQWA-LINEruniscompletedfirstandbackingfilesstored.Thesesamebackingfilesmaybeusedforboth1Dand3Dmodelruns,thetypeofrunbeingdefinedintheAQWA-WAVEdatafile.ThisfilealsodefinestheloadcasesrequiredfromtheAQWA-LINErunandthefilenamefortheASASmodel.Inthefigure,thepossibilitythatthe3Dmodelmaybeacomponentanalysisisshown.Inthisevent,theprogramwillautomaticallysearchforcomponentdatafiles,applyingloadsandrewritingthedataasrequired.AQWA-WAVEcanalsotransferAQWAfacetpressurestoANSYS®.Inordertousethisfacility,theusermustfirstcreateanequivalentASASmodelfromtheANSYSmodelusingtheANSTOASASmacroinANSYS.AfterrunningAQWA-WAVE,thestructuralloadinggeneratedcanbeimportedbacktotheANSYSmodelusingthe/INPUTcommandwhileinthesolutionprocessor.TheinterfacetoANSYScurrentlyhasthefollowinglimitations:•Hydrodynamicloadsonbeamsareignored(loadsonPIPEtypeelementscanbetransferred,however).•Thestructuralmodelmustbemodelledasasinglestructure,i.e.nosub-structurecomponents.2.2SelectionofWaveCasesAlargenumberofwavecasesmaybeselectedbytheuserintheAQWA-WAVEdata.ThisisachievedbydefiningawavefrequencynumberandawavedirectionnumberfromtheprecedingAQWA-LINEdataandthenspecifyingawaveheightandphasetobeassociatedwiththem.ThewaveheightisrequiredsincetheAQWA-LINErunisforunitwaveamplitudeandmustbescaledtotherequiredheight.ThephaseisnecessaryasthedragforcesthatcanbeproducedbytheprogramgenerallydonotvarysinusoidallyandcannotberepresenteddynamicallyasinAQWA-LINE.PressuresfromtheAQWA-LINEanalysisarethenextractedfromthebackingfilesandevaluatedfortheselectedheight/phaseasfollows:Optionally,staticpressuresmaybecalculatedandaddedtotheabovetimevaryingpressuresbythesettingofthe‘STAT’optionintheAQWA-WAVEdata.Therevisedpressureisthensimplygivenas:LoadcasescreatedbyAQWA-WAVEwillbewrittenbeforeanyotherASASloadcasesandwillbesequencedfrom1001unlesstheuserspecifiesadifferentloadcaseoffset(SeeLCOFcommandinSection3.1.5).2.3IncidentDiffractedandRadiatedWaveForcesIncident,diffractedandradiatedwaveforcesonthestructurearecalculatedbyAQWA-LINEforselectedwaveperiodsanddirections.Theseforcesmaybethoughtofasrelatingtoaunitwaveamplitude,althoughtheyareactuallyforcesperunitwaveamplitudeandrelatetoinfinitesimalwaves.TheincidentwaveforcesaresometimesreferredtoasFroude-Krylovforces.Theradiatedwaveforcesarezeroforafixedstructure.AQWA-LINEstorestheincident,diffractedandradiatedcomponentsofthepressuresontheindividualfacetsinabackingfile.Realandimaginarycomponentsofpressureareretained.ThewayAQWA-WAVEhandlesthesepressuresdependsonthetypeofASASmodelbeingloaded,tube/beammodelsorshell/solidmodels.Fortube/beammodels,groupsofAQWAfacets(specifiedbyelementgroupnumbers)maybeassociatedwithagivennodeorelementintheASASmodel.ThisdataisprovidedintheAQWA-WAVEdatafile.Inadditiontothegroupnumber,theusermustalsospecifywhichquadrantorhalfofasymmetricmodelistobeused.Provisionisalsomadefordefiningtheassembledcomponenttowhichtheelementornodebelongs.TheprogramwillevaluatetheincidentanddiffractedwaveforcesforeachfacetintheAQWAgroupattherequestedwaveheight,period,directionandphase(seeSection2.2).Itwillthensumtheseforcesaboutthenodeorelementcentroidrequested.SummedforcesatanodewillbeappliedasASASNodalLoads.Forcesonanelementwillbeappliedasdistributedloads.ElementsandnodesthatdonothaveAQWAgroupsassignedtothemwillnotbeloaded.Forsolid/shellelements,aspecialloadcase(loadcase1000)mustbepresentintheASASdataforanycomponentthathasanexternalwettedsurface.Componentswithnoloadcase1000willbeassumedtobewhollyinternal,orabovethewatersurface.ThisloadcaseshouldbeanASASfacepressureorunitloadcase,definingthewettedfacesofallwettedelements.(Note:Theactualloadvaluesareunimportant,onlythefacedataisusedbyAQWA-WAVE.)AQWA-WAVEevaluatespressuresfortherequestedwaveheight,period,directionandphase,inaccordancewithSection2.2,foreachnodeonthewettedsurfaceofeachelementthatappearsinloadcase1000.ElementsintheASASmodelgenerallywillnotcorrespondtofacetsintheAQWAmodelandsomemethodisclearlyneededtoobtainthesepressuresattheASASnodes.ThemethodcurrentlyadoptedistolocatetheASASnodeontheAQWAmeshandtheninterpolatethepressure.2.4MorisonLoadsAQWA-LINEdoesnotevaluatedragforcesonsubmergedcomponents.AQWA-WAVEthereforeallowsMorisonforcesonsuchcomponentstobecalculatedandaddedtotheincidentanddiffractedwaveforcesfromAQWA-LINE.Twotypesofcomponentareconsideredhere:1.RelativelylargediametertubularcomponentssimulatedusingfacetsinAQWA-LINE,butforwhichdragloadsareconsideredimportant(e.g.GBSshafts)2.Smallerdiametertubularmemberssubjecttodragandinertialoads(e.g.conductorframingonGBS).AlthoughprovisionismadeformodellingtheinertialoadsonsuchtubesinAQWA-LINE,thisisnottherecommendedmodellingforAQWA-WAVE,andthetubularmembersdonotneedtobemodelledinAQWA-LINE.WhenevaluatingMorisonloadsonsuchcomponentsofthestructure,severalfactorsneedtobeconsidered:•Theincidentflowisexpectedtobemodifiedbythepresenceofthemainstructureduetodiffractedwaveforces.TheparticlevelocitiesandaccelerationsonwhichtheMorisonforcesarebasedneedtoconsiderthiseffect.•Thelocalwatersurfaceduringthepassageofawaveisalsoexpectedtobemodifiedduetothepresenceofthestructure,thusaffectingtheextentofstructuresubjectedtowaveloading.A‘caissoneffect’(overallincreaseinwaterheight)anda‘rideup’onverticalmemberscuttingthesurfaceareexpected.•Theeffectsofcurrentvelocityondragshouldbeconsidered.Currentvelocitiesshouldalsobemodifiedtoallowforthepresenceofthestructure.•Althoughlinearwavetheoryisconsideredsufficientforevaluatingincidentanddiffractedwaveeffects,thisisoftennotsufficientfordragloadsnearthewatersurfacewheretheparticlevelocitiesandwatersurfaceelevationcanoftenbeinexcessofthatpredictedbysimpleAirytheory.Someconsiderationshouldbegiventotheeffectsofhigherorderwavetheory.•ThemethodofmodellingoftheASASstructureshouldbeconsidered.Althoughtheapplicationofdragandinertialoadstotubeelementsisrelativelystraightforward,somefurtherruleneedstobeprovidedtoassignpressurestotubularstructuresdefinedbyplateorsolidelements.Theaboveconsiderationsareaddressedinthefollowingtwosectionsundertheheadingsoffluidflowandloadapplication.2.4.1FluidFlowAtanypointintheflowoutsidetheAQWAfacetmodel,theincidentanddiffractedwaveflowpotentialcanbecalculatedusingthesameGreen’sfunctionroutinesasAQWA-LINE.Therateofchangeofpotentialineachprincipaldirectiongivesthevelocityoftheflowforthatdirection.Theeffectofallcontributingfacetsisconsidered.Thesecanbeaddedasavectortotheincidentflowtogivethedisturbedflowaroundthestructure.Waterparticleaccelerationsarederivedsimplyfromtherateofchangeofvelocity.Acurrentprofile(variationofcurrentwithdepth)maybespecifiedintheAQWA-WAVEdataforeachwavecaseandphaseselectedfromtheAQWA-LINEanalysis.Thecurrentflowisassumedtobehorizontalbutthedirectionmayvarywithdepth.Foreachgivenpoint,acurrentvelocityisthencalculatedbylinearinterpolationtotherequireddepth.Thisvelocityisagainsummedasavectortothewavevelocityinthedisturbedflow,calculatedasabove.Theuser-definedcurrentprofileisassumedtoincludetheeffectsofthestructuredisturbingtheflow.Theprogramdoesnotmodifythecurrentvelocitiesasitdoesforwaves.PrinciplesofmomentumpreservationorevenrunsofAQWA-LINEwiththecurrentrepresentedasalongdurationwavemaybehelpfulindeterminingthismodifiedprofile.Flowaroundamassiveobjecttendstocausealocaldistortionofthestillwatersurfaceknownasa‘caissoneffect’andwatertendsto‘rideup’membersthatcutthewatersurface.Thelattereffectisnormallynotconsideredtosignificantlychangegloballoadonthestructure,butisofsomeimportancetolocaldesign,particularlywaveslam,slapandthedeterminationoftherequiredairgap.The‘caissoneffect’issignificantonGBStypestructuresandcanresultinthetotalloadbeingappliedhigherupinthestructure.AQWA-WAVEcalculatesmostofthiseffect,whichisduetothediffractedwave.(Theincreaseinwaveelevationduetodiffractionmaybeobtainedexplicitly,usingthefieldpointfacilityinAQWA-LINE.Thepressureatagivenpointatthestillwaterlevelmaybeobtainedusingthismethodandthedynamicdisplacementofthewatersurfacemaybederivedfromthesimpleh=p/(ρg)formulation.)Theeffectofthisartificialraisingofthewatersurfaceissimplytoincrease(ordecreaseifnegative)theextentofstructuresubjecttowaterpressureloads.Ifapositivevalueisfound,theundisturbedwater-surfacemotionsareassumedtoapplyovertheincreaseindepth.Otherwise,themotionsarecutoffatthereducedwatersurface.HigherorderwavetheorymayproducehigherloadsthansimpleAirytheoryandtypicallyaccountforaraisingofthewatersurfaceelevationatthecrestandasmoothingofthetrough.AlthoughnotdealtwithexplicitlybyAQWA-WAVE,theusercanattempttomodeltheeffectbyinputtingascaled-upwaveheight,obtainedusingasuitablescalingfactor.Itissuggestedthatanestimateforthisfactorbeobtainedfromaprogramthatdoesallowfordifferentwavetheories,suchasASAS-WAVE.2.4.2LoadApplicationSmalldiametertubularmembersarehandledasbelow:•Thewatersurfaceelevationsattheendsoftheelementareevaluatedwithdueallowanceforthelocalincreaseordecreasementionedabove.•Ifbothendsoftheelementarebelowthewatersurface,thenthememberisfullyloaded.•Ifneitherendoftheelementisbelowthewatersurface,thenthememberisunloaded.•Ifonlyoneendoftheelementisinthewater,thememberisloadedoverthewettedlengthonly.•Thefluidflowateachendofaloadedlengthisevaluatedinaccordancewith2.4.1.•ThefluidflowsateachloadedendaretransformedintoloadsperunitlengthperpendiculartothememberusingMorison’sequationasbelow:F=0.5ρCdDuu+CmρAaWhereF=theforceperunitlengthCd=thedragcoefficientρ=themassdensityofwaterD=thememberdiameteru=theinstantaneousvelocityresolvednormaltothememberCm=theinertiacoefficientA=thecross-sectionalarea=πD2/4a=instantaneousaccelerationresolvednormaltothememberNote:Cm=1+CaWhereCa=theaddedmasscoefficient.TheaddedmasscanbeignoredbysettingCmtozero.However,ifCmissettoavaluelessthanone,butnotzero,anegativeCawillbeusedastheCm=1+Carelationshipisrespected,hencethevalidvaluesforCmare0or≥1.TheusershouldtakeintoaccountmarinegrowthwheninputtingthediameterintotheAQWA-WAVEdata.ThedragandinertiacoefficientscanbedefinedexplicitlybytheuserforalltubeelementsintheASASmodel.Memberswithnocoefficientswillnotbeconsidered.ThecoefficientsoccurintheAQWA-WAVEdataandarereferencedbyASASelementnumberandassembledcomponentname.•DistributedloadsontheelementarewrittentotheoutputdatafileasASAS‘BL6'typedistributedloads.Note:TheusermustnotdefineeitherOFFSETSorLOCALAXESfortubeelementsintheASASgeometrydeck.LargeAQWAsubstructures,whichhavecylindricalsymmetry(suchastheshaftofaGBS)andwhichhavebeenmodelledinAQWA-LINEusingPLATEelementscanalsohavetheirdragloadscalculatedbyAQWA-WAVE.Suchsubstructuresarereferredtohereas‘AQWAcomponents’.(AnAQWAcomponentwillcorrespondtooneormoreASAScomponents.)Ignoringcurrentforthemoment,theflow‘seenby’anAQWAcomponent,atanyinstantoftime,istakentobetheflowwhich,atthatinstant,isbeingexactlycancelled(normaltoeveryplate)bythecombinedflowduetoallthehydrodynamicsourcesonthecomponent.Theflow‘seenby’thecomponentcanthusbecalculatedbyadding,totheincidentflow(assumedundisturbed),theflowduetoallthehydrodynamicsourcesonthewholeAQWAstructure,EXCEPTthoseonthecomponent.Theresultingflowisevaluatedonthecentralaxisofthecomponentand(afteraddingtheconstantcurrent)usedinMorison’sequationtocalculatethedrag.TheprogramhasnoknowledgeofwhatconstitutesanAQWAcomponent.Ifitisrequiredtocalculatethedragonsuchacomponent,alltheelementswhichconstitutethecomponentmustbespecifiedintheAQWA-WAVEdata(seeOMITcommandinSection3.1.7),sothatthecorrespondinghydrodynamicsourcescanbeOMITTEDfromthedragcalculations.Twocasesneedtobeconsidered:a)ThetubularshaftisrepresentedbytubeelementsintheASASmodel.b)Thetubularshaftisrepresentedbysolidorshellelementshavingawettedsurface,asinSection2.3.Forcesonatubeelementidealisationoftheseshaftsmaynowbecalculatedexactlyasbefore,exceptthatinertialoadingisnotgenerallyrequiredandshouldbepreventedbysettingCmtozero.Shellorsolidelementmodelsrequiremoredata.SuchelementsshouldbearrangedintoASASgroups,eachofwhichrepresentsaringofelements.Theendco-ordinates,diameteranddragcoefficientsforeachsuchringaregivenintheAQWA-WAVEdata.RingsarereferencedbyASASgroupnumberandassembledcomponentnameintheAQWA-WAVEdata.Withtwoends,adiameterandadragcoefficient,eachringcannowbehandledexactlyasfortheabovetubesasfarastheevaluationofdistributedloadsonthelengthoftubular.Thedistributedloads(whichvaryfromendtoend)nowneedtobeassignedaspressureloadsontothewettedfaces.Fortunately,thereisampleliteraturetoshowthelikelydistributionofdragpressurearoundsuchacylinderandapressuredistributionasillustratedinFigure2-2isused.Theco-ordinatesofeachnodeateachelementoftheringisfoundandtransformedrelativetothestartandendofthetubeitrepresents.Fromthis,apressurecanbederivedaccordingtoFigure2-1.Thedragloadsonthetubularelementsandthepressuresontheelementsoftheringsareevaluatedasaboveandaresummedwithincident/diffractionloadscalculatedinaccordancewithSection2.3,priortobeingwrittentotheoutputASASdatafileintheappropriateformat.Itshouldbenotedthattheabovetreatmentofthewatersurfaceelevationandlinearisationofpressureloadsisrelativelysimplistic.Excessiveerrorswilloccuriftheelementmeshistoocoarse,particularlynearthewatersurface.Thisshouldberememberedwhenmeshingthemodel.2.5InertialLoadsForfloatingstructures,AQWA-WAVEwritesbodyforceandangularaccelerationcardsintotheASASLOADdecksofallcomponentscontainingmassiveelements.WhenASASisrun,thesewillgenerateinertialloadstobalancethepressureloadstransferredfromAQWA-LINE.Ifthe‘STAT’optionisselected,thenstaticaccelerationswillbeadded,tobalancethehydrostaticpressureswhichareincludedwhenthisoptionisinvoked.IfthefloatingstructureisinequilibriuminAQWA-LINE(asitshouldbe)thenthestaticaccelerationwillsimplybetheaccelerationduetogravity.Forfixedstructures,thereisnodynamicaccelerationandaccelerationcardswillonlybeoutputifthe‘STAT’optionisselected.Inthiscase,theaccelerationoutputisalwaystheaccelerationduetogravity.WhenASASisrun,thiswillcreateinertialloadsequal(intotal)totheweightofthestructure.Theusershouldnotethatthereisnoforcebalanceinthecaseoffixedstructures,sincethereactionattheseabedisnotmodelledinAQWA-WAVE.2.6UnitsProvisionismadeforthecasewheredifferentunitsareusedinAQWAandASAS.AQWA-WAVEneedstoknowwhattheASASlengthunitsareandASASneedstoknowwhattheAQWAloadunitsare.TheusermustsupplythisinformationintheAQWA-WAVEdatafile(seeSCALandUNITcommandsinSection3.1.6),iftheunitsarenotconsistentbetweenAQWAandASAS.详细内容请见附件免责声明：本页面/内容部分素材来源于互联网公开信息，旨在传递更多信息，不代表本平台立场。版权归原作者或机构所有，如涉及侵权，请通过平台联系我们，我们将在核实后第一时间处理。本平台对转载内容的真实性、准确性不作任何保证，用户需自行判断并承担使用风险。
