流体力学(英文资料)PPT文件格式下载.ppt
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FluidMechanicsFrankM.White气体动力学基础潘锦珊等Teachers:
陆利蓬王洪伟邹正平(4-5班)李秋实景晓东李志平(1-3班)Grades:
30%homework+70%finalexam,ContentsChapter1Introduction(6hours)Chapter2FluidStatics(4hours)Chapter3IntegralRelations(12hours)Chapter4DifferentialRelations(8hours)Chapter5BoundaryLayer(6hours)Chapter6FlowCompressibility(2hours)Chapter7Vorticity(4hours)Summary(2hours),Chapter1Introduction,1.1PreliminaryRemarksWhenyouthinkaboutit,almosteverythingonthisplaneteitherisafluidormoveswithinornearafluid.-FrankM.White,Someexamples,Jupiter,Humanplume,Wingtipvortex,Tornado,A3807379.824.2(m),An-2258488.418.1(m),Aturbofan(涡扇)jetengine,;
CFM56inMTU,WhatisFluidMechanics?
FluidMechanicsisthestudyoffluideitherinmotion(FluidDynamics流体动力学)oratrest(FluidStatics流体静力学)andsubsequenteffectsofthefluidupontheboundaries,whichmaybeeithersolidsurfacesorinterfaceswithotherfluids.,Whatisafluid?
Theconceptofafluid,Asolidcanresistashearstress(剪切应力)byastaticdeformation.Afluidcannotresistashearstressbyastaticdeformation.Anyshearstressappliedtoafluid,nomatterhowsmall,willresultinmotionofthatfluid.Thefluidmovesanddeformscontinuouslyaslongastheshearisapplied.,HistoryandScopeofFluidMechanics,Pre-history:
Sailingshipswithoars(橹桨)andirrigationsystemwerebothknowninprehistory,Archimedes(285-212BC),ParallelogramlawforadditionofvectorsLawofbuoyancy,曹冲(196-208),LeonardodaVinci(1452-1519),Equationofconservationofmassinone-dimensionalsteadyflowExperimentalistTurbulence,IsaacNewton(1642-1727),LawsofmotionLawsofviscosityofNewtonianfluid,18thcentury,Mathematicians:
Euler(欧拉):
EulerequationBernoulli(伯努利):
Bernoulliequation,Idealflowsolutions,DAlembert(达朗贝尔):
DAlembertparadox(佯谬,疑题),Engineers:
Hydraulics(水力学)relayingonexperiment,Channels,Shipresistance,Pipeflows,PitotVenturiTorricelliPoiseuille,19thcentury,Navier(1785-1836)&
Stokes(1819-1905)N-Sequation,Reynolds(1842-1912)TurbulenceFamousexperimentontransitionReynoldsNumber,20thcentury,LudwigPrandtl(1875-1953),钱学森(1911-2009),陆士嘉(1911-1986),Boundarylayertheory(1904)Tobethesinglemostimportanttoolinmodernflowanalysis.,Thefatherofmodernfluidmechanics,VonKarman(1881-1963),1.2SomePropertiesoffluids,
(1).viscosity(粘性)*Definition:
Whenafluidissheared(剪切),itbeginstomove.Subsequently,apairofforcesappearontheshearsurface,whichresiststheshearmotionofthefluid.Thisiscalledviscosity.,*Thenatureofviscosity:
Forliquiditiscohesion(结合)(oil_00100.mov),Forgasitisthetransportofmomentum(动量输运)(Particle_flow.mov),Velocitygradient,*Newtonianlawofviscosity(牛顿粘性定律,牛顿内摩擦定律),Shearstress,Thevelocitygradientiscomparabletodeformation.,ThiskindoflinearfluidiscalledNewtonianfluid.(牛顿流体),Realfluid(Viscous),Idealfluid(Inviscid&
Frictionless),Forcertainfluid,misfunctionoftemperature.(liquids,gases),m:
CoefficientofviscosityDynamiccoefficientofviscosity(动力粘性系数)Ns/m2,n=m/r:
Kinematiccoefficientofviscosity(运动粘性系数)m2/s,
(2).Compressibility(压缩性),Incompressible(不可压):
r=constMostliquidflowsaretreatedasincompressible.Only1%increaseifpressureincreaseby220,Compressible(可压缩):
r=r(P,T)Gasescanalsobetreatedasincompressiblewhentheirvelocityislessthan0.3Manumbers,(3).StateRelationsforGasesPerfect-gasLaw(理想气体状态方程),ErnstMach,R=287.06forair,(4).ThermalConductivity(热传导),:
heatfluxinndirectionperunitareak:
coefficientofthermalconductivityT:
temperaturen:
directionofheattransfer,Fourierslawofheatconduction,1.3TheFluidasaContinuum(连续介质),Density(密度),Elementalvolume(流体微团、流体质点)Largeenoughinmicroscope(微观)10-9mm3ofairatstandardconditionscontainsapproximately3107molecules.,Mostengineeringproblemsareconcernedwithphysicaldimensionsmuchlargerthanthislimitingvolume.,Suchafluidiscalledacontinuum,whichsimplymeansthatitsvariationinpropertiesissosmooththatthedifferentialcalculuscanbeusedtoanalyzethesubstance.,*Smallenoughinmacroscope(宏观).,微观无穷大宏观无穷小,Sodensityisessentiallyapointfunctionandfluidpropertiescanbethoughtofasvaryingcontinuallyinspace.,1.4Surfaceforce(表面力)andbodyforce(质量力,体积力),Surfaceforcesactcontinuouslyonthesidesurfacesoffluidelements.Pressure,friction.Contactsurfaceforceperunitarea(单位面积)(应力),Bodyforcesactontheentiremassoftheelement.Gravity,electromagnetic.NocotactPerunitmass(单位质量)g,1.5Twodifferentpointsofviewinanalyzingproblemsinmechanics,*TheEulerianview(欧拉观点)andtheLagrangianview(拉格朗日观点)TheEulerianviewisconcernedwiththefieldofflow,appropriatetofluidmechanics.,TheLagrangianviewfollowsanindividualparticlemovingthroughtheflow,appropriatetosolidmechanics.,Thecontrastoftwoframes,*Flowclassification(流动分类),Ac