美赛培训论文Word文档格式.docx
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Ourdestinationistotrackthelitterdebrisandforecastitsfutureconditionstohelpmanagingit.Aftertheanalysis,wefindthatthevelocityoftrashalleviatesastimegoeson.Trashdoesitsmotionintwoprobableways,oneisduetoresistancesgivenbyseawater,andanotherisduetodampedvibration.Byusingclassicphysicaltheories,wecapturemainmotivespropellingtrashintotheSouthPacificGyre.That’showthegreatgarbagepatchforms.
Accordingtothemodelandtheitsresult,weformulatethemonitoringprogram.
Comparedwiththephysicaltruth,themodelalsohassomeunsatisfactoryaspects,butithassomereference.
Introduction
Whereeveristheworld’slargestdump?
ItislocatedinthePacificOcean,aboutonethousandsixhundredkilometerswestofCalifornia,calledtheGreatPacificOceanGarbagePatch.Accordingtopertinentdata[1],itistenmilliontonsofdebrislitterthatispilingupthere,likeaplasticsoupwhenpeoplearelookingahead.And80percentofthetrashisfrommaincontinents,10percentconsistsofusednetsorotherfishingtoolsandtheother10percentoftrashisfrompassing-byships.Mostofthegarbageislandsareinoceanicgyres.Nowadays,awidevarietyoftechnicalandscientificproblemsassociatedwiththisdebrismassarecomingtolight.Butuntilnow,noonecanreasonoutit’scoverageareaexactlyandthegreateconomiclossesecologicalimpactandthePacificOceanGyrehascaused.
Long-termeffectivemethodsaresearchedtoobjectivelycharacterizetheGyre.TheoceancurrentisthemechanismoftheGreatPacificOceanGarbagePatch.Inourpaper,wewilltakethesouthpacificoceangarbagepatchforexample,focusingonhowthedebrislitterdriftsinthefluid,assemblesinquantity,distributesundertheeffectofoceancurrentsin.Afterwards,inaccordancewithourmodel,weprojectprocessreasonablesuggestionstomonitortheGyre,trackingit’sgrowth.
Assumptions
1.Regardlessoftimeandgeographicalposition’simpactsonthespeedoftheoceancurrents,weconsiderthespeedasconstantvalue.
2.Accordingtothedatum[2],wedesignatethespeedofthewestwinddriftvp1as1.4km/h,thatofPeruCurrentvp2as1km/h,thatofthesouthequatorialwarmcurrentasvp33km/h,thatofthenorthAustraliacurrentasvp41.4km/h.
3.RegardtheflowofthecurrentsasstationaryflowandtheseawaterasNewtonianfluid,whichmeanstheviscosityoftheseawaterisconstant.
4.Considertheleveloftheseaisinlaminarflow.
5.Themasspoint’smotionintheseacanbeinfluencedbytheoceancurrentnomatterhowfarthemallpointisawayfromit.
6.Themasspoint’smotionissynthesizedbythesub-movementofperoceancurrentregardlessofeffectsofotherfactors.
TheModel
Inourmodel,wewillutilizedynamicanalogtoexpoundtheformationoftheoceangarbagepatch.Themodelsubstitutesstraightlinesforoceancurrentswhichformthegyre,inthemodeltheorientationofthestraightlinerepresentativeoftheflowdirectionandthespeedvalueretrospecttotheassumptionNo.4.Sequentially,wesimplifythephysicaltruthasthatshowninthefigure1.(DuetothechangeofthedirectionofthePeruCurrentonpassage,thesimplifiedmodelreplacestowstraightlines,whichareofthesamespeedbutdifferentdirection,ofthePeruCurrent.)
Figure1:
theDistributionoftheOceanCurrentsintheSouthPacificOcean
Then,ourmodeltalksoverhowtheoceancurrenteffectthemasspoint’smovement,morespecifically,theeffectonthevelocityofthedirectionparalleltothelineandperpendiculartotheline.
Let’sdiscusstheeffectonthemasspoint’svelocityofthedirectionparalleltothelinefirstly.
AccordingtotheassumptionNo.3andNo.4andtherelativeinformation[3],wecandescribetheoceancurrentflowasone-dimensionalsteadyflow.OnthebasisofNavier-StokesEquationshowbelow
YmeansthemassforceofthedirectionY-axis,inourmodel;
ρmeansthedensityofseawater;
νmeansthekinematicviscosityofseawater,,μmeansthedynamicviscosityofseawater.Wecansimplifytheequationaboveandgettheonebelow
Integrateandget
(1)
Soweplugtowboundaryconditions
(2)shownbelowintotheformula
(1)
integralconstantisdetermined
Since,so
(2)
Wecanmakeaconclusionthatthemasspoint’svelocityinthedirectionparalleltotheoceancurrentisthesameasthatoftheoceancurrent.
Secondlywefocusonthemasspoint’velocityinthedirectionperpendiculartotheoceancurrent’sdirection.
Havingconsultedsomemate