02AQWA-Example--–-A-tanker-and-bouy

©2006ANSYS,Inc.Allrightsreserved.1ANSYS,Inc.ProprietaryExampleAQWAanalysis–AtankerandbouyAQWA-Line+AQWA-DriftZhenglinCao©2006ANSYS,Inc.Allrightsreserved.2ANSYS,Inc.ProprietaryWhoisthiscoursefor?Aimedat•ThisdocumentsummarizeshowAQWAcanbeusedtosimulatetheslowdriftmotionofatankermooredtoabuoy.•Toruntheanalysisexecutealtakbuy.datfollowedbyadtakbuy.dat.©2006ANSYS,Inc.Allrightsreserved.3ANSYS,Inc.Proprietary•Thestudyconsideredagenericvesseloflength230m,maximumbeam41m,draft15manddisplacement124,256tonnes.©2006ANSYS,Inc.Allrightsreserved.4ANSYS,Inc.Proprietary•Thevesselwastiedtoabuoywithanelasticcatenarylinewiththefollowingproperties:•Onehundredsecondsfromthestartofthesimulationthelinewassettobreak.LengthMass/UnitLength*EA**150.01506E8©2006ANSYS,Inc.Allrightsreserved.5ANSYS,Inc.Proprietary•Thebuoywasmooredtotheseabedwith4similarlines:LengthMass/UnitLength*EA**601507.5E61001207.5E6701707.5E6•*Massoflinelessthemassofthedisplacedwater•**E(Youngsmodulus)timesA(crosssectionalarea)•N.B.definitionsstartfromtheanchorpoint.©2006ANSYS,Inc.Allrightsreserved.6ANSYS,Inc.Proprietary•ModelGeneration•TheshipmodelwasautomaticallygeneratedbytheAQWAGraphicalsupervisorfromalines-planfile,whichdescribestheprofileofthevesselatseverallocationsalongitslength.•Thebuoymeshwasgeneratedmanually.©2006ANSYS,Inc.Allrightsreserved.7ANSYS,Inc.Proprietary•AQWA-LINE•AQWA-LINEcalculatesthelinearresponseofafloatingbodyorbodiesinregularwaves.TheprogrammaybeusedseparatelyorinassociationwithotherprogramswithintheAQWASuite.TheprincipalanalysistechniqueusedwithinAQWA-LINEisRadiation/Diffractiontheory.Thistypeofanalysisisusuallyusedonbodieswhosecharacteristicdimensionscausescatteringoftheincidentregularwaves.Thecalculationprovidesthefirstandsecondorderwaveloadingsonafloatingorfixedbody.©2006ANSYS,Inc.Allrightsreserved.8ANSYS,Inc.Proprietary•AQWA-DRIFT•AQWA-DRIFTsimulatesthemotionoffloatingstructuresarbitrarilyconnectedbyarticulationsormooringlinesundertheactionofwind,waveand/orcurrentforces.Theprogramhasthefollowingtwomodesofoperation:•1.Slowdriftmode,inwhichthestructureissubjectedtoonlythesecondorderwaveforces,steadywindandcurrent;•2.Wavefrequencymode,asinthisexampleinwhichbothslowdriftandwavefrequencyforcesareincludedalongwithsteadywindandcurrent.•Theprogramrequiresafullhydrostaticandhydrodynamicdescriptionofeachstructure.ThiscaneitherbeinputasdataortransferreddirectlyfromtheoutputresultsofanAQWA-LINEanalysis.©2006ANSYS,Inc.Allrightsreserved.9ANSYS,Inc.Proprietary•WindandWaveConditions•APierson-Moskowitzspectrumwithsignificantwaveheightof4mwasused.•Awindof25m/sandacurrentof1m/swerespecifiedat15degreestothevessel.Typicalwindandcurrentforcecoefficientsforavesselofthistypewereset,torepresenttheforcesactingontheship.©2006ANSYS,Inc.Allrightsreserved.10ANSYS,Inc.Proprietary•Results•Thesegraphsshowthetensioninthelineconnectingthevesselandbuoyandthehorizontalmovementofthevesselduringthecourseofthesimulation.Thebreakingofthelinecanclearlybeseenat100seconds.©2006ANSYS,Inc.Allrightsreserved.11ANSYS,Inc.ProprietaryAnnotatedAQWA-LINEFile•JOBMESHLINE•TheJOBcardspecifiesthetypeofanalysistoberun.InthiscasetheAQWA-LINEprogramwillbeused.Afourcharacteruser-definedcaseidentifier,inthiscaseMESHisalsoinput.•TITLEASHIPANDABUOY•Thetitleoftherunisspecified,thiswillappearonthegraphicalandtextfileoutput.©2006ANSYS,Inc.Allrightsreserved.12ANSYS,Inc.Proprietary•OPTIONSRESTGOONLDOPEND•Variousoptionsmaybeset,inthiscasethefollowingareused:•REST–NeededifaRESTARTcardisinput,seebelow.•GOON–Allowsanalysisto“GOON”despitecertainmodelruleviolations.•LDOP–PerformsLoadoutput,whichisnecessaryifstressanalysisistobeperformed.•END–Indicatestheendoftheoptionslist.•N.B.manymoreoptionsareavailable,seereferencemanual.©2006ANSYS,Inc.Allrightsreserved.13ANSYS,Inc.Proprietary•RESTART13•TheRESTARTcarddescribesthestagestoberun.InAQWA-LINEanalysessuchasthis,onlystages1to3arenormallyexecuted,stages1to3are:•Stage1-GeometricDefinitionandStaticEnvironment•Stage2-InputoftheDiffraction/RadiationAnalysisParameters•Stage3-TheDiffraction/RadiationAnalysis©2006ANSYS,Inc.Allrightsreserved.14ANSYS,Inc.Proprietary•Deck1•01COOR•Thisdeckdescribesthecoordinatesofthenodepoints.•013001611.00000.00000.00001.00.00.0•Thislinecreatessixnodes,thedataonthislineisasfollows:•“01”incolumns5and6isanoptionalidentifier.•3001–Thenumberofthefirstnodetobecreated.•6–Sixnodeswillbegenerated.•1–eachnodenumberwillbeincrementedby1.I.E.nodes3001,3002,3003etcarecreated.•1.00000.00000.0000–Thecoordinatesofthefirstnode.•1.00.00.0–Thecoordinateincrementsforsubsequentnodes.•~Dataomitted~©2006ANSYS,Inc.Allrightsreserved.15ANSYS,Inc.Proprietary•R61000.00000.0000.0000.00.015.0•The“R”atthestartofthislineindicatesthatnodeswillbegeneratedwithanangularoffset.Allnodesgeneratedthusfarwillbecopiedsixtimeswithanodenumberoffsetof100.Nodeswillbetranslatedabout0,0,0withanoffsetof15degreesabouttheZaxiseachtime.(Thesenodesareusedinthecreationofthebuoy)•~Remainderofbuoynodesomitted~©2006ANSYS,Inc.Allrightsreserved.16ANSYS,Inc.Proprietary•1115.0000.0000.000•Nodesforthev