简介：垂直地在免费表面上侵犯的一口2D槽喷气的流动特征被大埃迪模拟(LES)数字地与一个动态Sub-GridScale(SGS)模型一起调查。σ-坐标转变被介绍印射深度变量物理领域到一件深度制服计算领域。裂口操作员计划，把答案过程切成移流，散开和压力繁殖步，被采用解决即时速度和压力地。一个充分非线性的Lagrange-Euler方法被用来计算免费表面举起。数字结果证明喷气在Eestablished流动(ZEF)的地区保留你方类似，当喷气的骚乱逐渐地变从时对各向同性在表面冲击(ZSI)的地区各向异性。当喷气接近免费表面时，中心线速度很快减少并且流动被免费表面偏斜。二口对称的表面喷气在水平喷气(ZHJ)的地区被形成。超高的AnapproximateGuassian分发也在免费表面上被形成。Thecomputed结果在对可得到的试验性的数据的好同意。

简介：ResultsofseveralLargeEddySimulations(LES)ofopenchannelflowswithnon-submergedvegetationarepresentedinthisarticle.Itisshownthatthevegetationcanmaketheflowstructureinthemainstreamdirectionuniformforbothsupercriticalandsubcriticalflows.Forsubcriticalflows,theLESresultsoftheensemble-averageoftime-averagedvelocitydistributionsatfourverticalsectionsaroundasingleplantareingoodagreementwithmeasurements.Thevelocityseesdoublepeaksattheupperandlowerpositionsofflows.Forsupercriticalflows,theensemble-averagevelocitiesseesomediscrepancybetweenLESandmeasurementresults.Somesecondaryfloweddiesappearnearthesingleplant,andtheyjustlocateinthepositionsofthedoublepeaksinstream-wisevelocityprofiles.ItisalsofoundthatthevegetationdragcoefficientdeceasesastheFroudenumberincreases.

简介：WithrespecttothecrestspillwaywithlargeunitdischargeandlowFroudenumber,thehydraulicsoftheslit-typeenergydissipaterattheoutletshouldbenoticedduetothecomplicatedflowregimes.Inthepresentpaper,someissuesabouthydrauliccharacteristicswereexperimentallyinvestigatedbymeansoffiveslit-typeoutletsandfourtetrahedrons,includingtheflowchoking,impacttoriverbanksandjettrajectory.Themainfindingsareasfollows.ThecriticalFroudenumberfortheflowchokingdecreaseswithincreasingoutletwidthoftheslit-typeenergydissipater.IftheflowFroudenumberisexpressedbytheparametersjustbeforethisenergydissipater,thetetrahedronplacedinsidethesidewalloftheoutletcouldefficientlyavoidtheflowimpacttotheriverbankofsameside,andcomparedwiththejettrajectoryoftheslit-typeenergydissipater,theoutletwithtetrahedronhasdifferenttrajectorytrend,i.e.,thedistanceofthejettrajectorydecreaseswiththeincreaseofthewaterheadduetospecialformoftheoutlettetrahedron.

简介：TheFilteringGridScale(FGS)ofsub-gridscalemodelsdoesnotmatchwiththetheoreticalProperFGS(PFGS)becauseoftheimpropermesh.Therefore,properLargeEddySimulation(LES)Meshisverydecisiveforbetterresultsandmoreeconomicalcost.Inthiswork,thepurposeistoprovideanadaptivecontrolstrategyforproperLESmeshwithturbulencetheoryandCFDmethods.AnewexpressionofPFGSisproposedonthebasisof-5/3lawofinertialsub-rangeandthepropermeshofLEScanbebuiltdirectlyfromtheadjustmentofRANSmesh.Abenchmarkofthebackwardfacingstepflowatisprovidedforapplicationandverification.Therearethreekindsofmeshsizes,includingtheRANSmesh,LAM(LESofadaptive-controlmesh),LFM(LESoffinemesh),employedhere.ThegridnumberofLAMissmallerthanthoseofLFMevidently,andtheresultsofLAMareinagoodagreementwiththoseofDNSandexperiments.ItisrevealedthattheresultsofLAMareveryclosetothoseofLFM.Theconclusionsprovidepositiveevidencesforthenovelstrategy.

简介：Thefeaturesofunsteadyflowsuchaspressurevariationandfluctuationinalargehydraulicturbineusuallyleadtotheinstabilityofoperation.Thisarticlereportstherecentinsiteinvestigationconcerningthecharacteristicfrequenciesinpressurefluctuation,shafttorsionaloscillationandstructuralvibrationofaprototype700MWFrancisturbineunit.Theinvestigationwascarriedoutforawideloadrangeof200MW-700MWintheconditionofwaterhead57m-90m.Anextensiveanalysisofbothtime-historyandfrequencydataoftheseunsteadyhydraulicbehaviourswasconducted.Itwasobservedthatthepressurefluctuationinadrafttubeisstrongerthanthatinupstreamflowpassage.Thelowfrequencywithaboutonethirdofrotationfrequencyisdominativeforthepressurefluctuationinpartloadrange.Alsotheunsteadyfeaturesofvibrationofheadcoverandtorsionaloscillationofshaftexhibitedthesimilarfeatures.Numericalanalysisshowedthatthevibrationandoscillationarecausedbyvortexropeinthedrafttube.Inaddition,astrongvibrationwithspecialcharacteristicfrequencywasobservedfortheheadcoverinmiddleloadrange.Thepressurefluctuationinthedrafttubewiththesamefrequencywasalsorecorded.Becausethisspecialvibrationhasappearedinthedesignednormalrunningcondition,itshouldbeavoidedbycarefullyallocatingpowerloadinthefutureoperation.

简介：现在的学习考虑发展混合被开始二条免费溪流合并形成的层由一个裂解槽盘子分开了。在粒子分散上调查旋涡的结构的影响，当时，数字模拟被进行速度比率，定义为R=U_∞-U_(-∞)/U_∞+U_(-∞),是0。5。大旋涡的模拟(LES)被采用理解大规模旋涡的结构的效果在质点分散上由theKelvin-Helmholtz不稳定性发源。有粒子的苍蝇灰缩放10，50,100，150，并且200um分别地在二维的混合层的起源被装载。Itis证实粒子分散强烈取决于大规模旋涡的结构的运动。粒子分散被在经历配对相互作用的混合的层跟随粒子轨道数字地设想。

简介：Theboundaryelementmethod(BEM)isamainmethodforanalyzingtheinteractionsbetweenthewavesandthemarinestructures.AswiththeBEM,asetoflinearequationsaregeneratedwithafullmatrix,therequiredcalculationsandstorageincreaserapidlywiththeincreaseofthestructurescale.Thus,anacceleratedmethodwithalowstorageisdesirableforthewaveinteractionwithaverylargestructure.AsystematicreviewisgiveninthispaperfortheBEMforsolvingtheproblemofthewaveinteractionwithalargescalestructure.VariousintegralequationsarederivedbasedondifferentGreenfunctions,theadvantagesanddisadvantagesofdifferentdiscretizationschemesoftheintegralequationsbytheconstantpanels,thehigherorderelements,andthesplinefunctionsarediscussed.Forthehigherorderelementdiscretizationmethod,thespecialconcernsaregiventothenumericalcalculationsofthesingle-layerpotential,thedoublelayerpotentialandthesolidanglecoefficients.Foralargescalecomputationproblemsuchasthewaveinteractionwithaverylargestructureoralargenumberofbodies,theBEMswiththeFMMandpFFTaccelerationsarediscussed,respectively,includingtheprinciplesoftheFMMandthepFFT,andtheirimplementationsinvariousintegralequationswithdifferentGreenfunctions.Finally,somepotentialapplicationsoftheaccelerationmethodsforproblemswithlargescalecomputationsintheoceanandcoastalengineeringareintroduced.

简介：TheseparatedturbulentflowaroundacircularcylinderisinvestigatedusingLarge-EddySimulation(LES),Detached-EddySimulation(DES,orhybridRANS/LESmethods),andUnsteadyReynolds-AveragedNavier-Stokes(URANS).Thepurposeofthisstudyistoexaminesometypicalsimulationapproachesforthepredictionofcomplexseparatedturbulentflowandtoclarifythecapabilityofapplyingtheseapproachestoatypicalcaseoftheseparatedturbulentflowaroundacircularcylinder.Severalturbulencemodels,i.e.dynamicSub-gridScale(SGS)modelinLES,theDES-basedSpalart-Allmaras(S-A)andk?ωShear-Stress-Transport(SST)modelsinDES,andtheS-AandSSTmodelsinURANS,areusedinthecalculations.Sometypicalresults,e.g.,themeanpressureanddragcoefficients,velocityprofiles,Strouhalnumber,andReynoldsstresses,areobtainedandcomparedwithpreviouscomputationalandexperimentaldata.Basedonourextensivecalculations,weassessthecapabilityandperformanceofthesesimulationapproachescoupledwiththerelevantturbulencemodelstopredicttheseparatedturbulentflow.

简介：ＣＯＭＰＵＴＡＴＩＯＮＯＦＴＵＲＢＵＬＥＮＴＦＬＯＷＡＮＤＨＥＡＴＴＲＡＮＳＦＥＲＩＮＬＡＲＧＥＲＡＤＩＵＳ９０－ＤＥＧＲＥＥＣＩＲＣＵＬＡＲＢＥＮＤＳＭ．Ｊ．Ｗａｎｇ（ＴｅｃｈｎｉｓｃｈｅＵｎｉｖｅｒｓｉｔａｔＭｕｎｃｈｅｎ，ＢＲＤ）ＳｕＭｉｎｇ－...

简介：Anon-linearturbulenthydrodynamicmodelwasproposedbyZhanandLi(1993)usingthelargeeddysimulationapproachanddirectionaleddyviscositymethod.Themodelissimplifiedinthispaperandisappliedtotheproblemofasidedischargeintoopen-channelflow,whereareeireulationzonedevelopsdownstreamofthedischarge.Thenumericalresultsarecomparedwithexperimentalresults(StrazisarandPrahl(1973)andMikhail,Chu,andSavage(1975))andpreviousnumericalresultsobtainedusingak-εmodel(McGuirkandRodi,1978).Theagreementisgood.

简介：Physicalmodeltestswerecounductedtopredictlocalscourandmaximumscourdeptharoundthelargediametercylinderslocatedinthe(sand)seabedundertheactionofbothwaveandcurrent.Accordingtotheresultoftests,ananalysiswasmadeonallthefactorsinfluencingthescour.Theresultsshowsthatfortheseabedwithrelativefinegrainsinshallowwater(0.07＜h/L≤0.28),whentherelativediameterD/Lofthecylinderiswithin0.3-0.7,themaineffectivescourfactorsaroundthecylinderintheseabedarediameterDofthecylinder,thewaveheightH,thewavelengthL,thevelocityVcofthecurrentandtheparametersrelatedtotheseabedsoiltexture.Themainparametersinfluecingthemaximumscourdepthwereanalyzed,andthetestdataweresyntherized,toobtaintheformulapredictingthescourdeptharoundthelargediametercylinderundertheofbothwaveandcurrent.

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