流体力学复习资料及英文专有名词解释

Chapter1Fluidstatics流体静力学1.连续介质假定(Continuumassumption)：Therealfluidisconsideredasno-gapcontinuousmedia,calledthebasicassumptionofcontinuityoffluid,orthecontinuumhypothesisoffluid.流体是由连续分布的流体质点(fluidparticle)所组成，彼此间无间隙。它是流体力学中最基本的假定，1755年由欧拉提出。在连续性假设之下，表征流体状态的宏观物理量在空间和时间上都是连续分布的，都可以作为空间和时间的函数。2.流体质点（Fluidparticle）:AfluidelementthatissmallenoughwithenoughmolestomakesurethatthemacroscopicmeandensityhasdefinitevalueisdefinedasaFluidParticle.宏观上足够小，微观上足够大。3.流体的粘性（Viscosity）:isaninternalpropertyofafluidthatoffersresistancetosheardeformation.Itdescribesafluid'sinternalresistancetoflowandmaybethoughtasameasureoffluidfriction.流体在运动状态下抵抗剪切变形的性质，称为黏性或粘滞性。它表示流体的内部流动阻力，也可当做一个流体摩擦力量。Theviscosityofagasincreaseswithtemperature,theviscosityofaliquiddecreaseswithtemperature.4.牛顿内摩擦定律（Newton’slawofviscosity）：5.Thedynamicviscosity（动力黏度）isalsocalledabsoluteviscosity（绝对黏度）.Thekinematicviscosity（运动黏度）istheratioofdynamicviscositytodensity.6.Compressibility（压缩性）：Asthetemperatureisconstant,themagnitudeofcompressibilityisexpressedbycoefficientofvolumecompressibility(体积压缩系数)к,arelativevariationrate（相对变化率）ofvolumeperunitpressure.Thebulkmodulusofelasticity(体积弹性模量)Eisthereciprocalofcoefficientofvolumecompressibilityк.7.流体的膨胀性(expansibility;dilatability)：Thecoefficientofcubicalexpansion(体积热膨胀系数)αtistherelativevariationrateofvolumeperunittemperaturechange.8.表面张力Surfacetension:Apropertyresultingfromtheattractiveforcesbetweendudz2ddmNddVVVpVp1ddpEVVo1K,1CTdVVdVadTVdTmolecules.-----单位长度所受拉力9.表面力Surfaceforce——istheforceexertedonthecontactsurfacebythecontactedfluidorotherbody.Itsvalueisproportionaltocontactarea.作用在所研究流体外表面上与表面积大小成正比的力。Stress（应力）isthesurfaceforceonperunitarea.10.质量力Massforce——Theforceactingoneveryfluidmassparticlewithinthecontrolbody.Itsvalueisproportionaltoitsmass.Massforceisalsoknownasbodyforce.作用在流体的每一个流体质点上，其大小与流体所具有的质量成正比。11.EulerEquilibriumEquations欧拉平衡微分方程（分量式）1775年PhysicalMeaning:Forthefluidinequilibrium,surfaceforcecomponentspermassfluidareequaltomassforcecomponentspermassfluid.Pressurevariationrateinaxesdirectionsareequaltomassforcecomponentsperunitvolumeinaxesdirectionsrespectively12.constant-pressureSurface(等压面)——asurfacethatthepressureofeverypointinliquidisequal.Commonconstant-pressuresurfacesarefreeliquidsurfaceandinterfaceoftwounmixedfluidsinequilibrium.平衡流体中压强相等的点所组成的平面或曲面。13.PressureDistributionintheStaticFluid重力场中流体的平衡Conclusions:1.Pressureatapointinastaticfluidundergravityincreaseslinearlywithdepth.2.Pressureatapointinastaticfluidundergravityisequaltothesumofthepressureatthefreesurfaceandthefluidspecificweighttimingdepth.3.constant-pressuresurfaceinastaticfluidundergravityisahorizontalplane.4.Extended:whilethepressureatapointandthedepthdifferencebetweentwopointsareknown,thepressureatanotherpointcanbecalculated.14.Absolutepressure(绝对压力),Gagepressure(相对压力,又称“表压力”),andVacuum(真空度):表压力＝绝对压力－大气压力;真空度＝大气压力－绝对压力15.FluidinRelativeEquilibrium(相对静止流体)Equationofconstant-pressuresurface(等压面方程):a)UniformLinearAcceleration等加速度直线运动流体:111xyzpfxpfypfz(,,)pppxyz(,,)xyzfff0pCdp或CgpzCgzpcosd(sin)d0ayagzb)UniformRotationaboutaVerticalAxis等角速度旋转流体:Chapter2basicequationsoffluidmechanics16.迹线pathline：thetraceafterasingleparticletravelsinafieldofflowoveraperiodoftime.流体质点的运动轨迹曲线17.流线streamline：acurvethatshowthedirectionofanumberofparticlesatthesameinstantoftime.某一时刻处处与速度矢量相切的空间曲线--瞬时性。18.Stream-tube(流管)——Consideraclosedcurve(notstreamline)intheflowfield,thendrawstreamlinesthrougheverypointonit,soastoformatube-shapingspacewhosewallsarestreamlines.Thistubeiscalledthestream-tube.在流场中任取一个有流体从中通过的封闭曲线，在曲线上的每一个质点都可以引出一条流线，这些流线簇围成的管状曲面称为流管。19.Tube-flow流束——Fluidfullingthestreamtubeiscalledthetube-flowandthelimitofatube-flowisastreamline.流管内的全部流体称为流束。20.Ministream-tube微小流束——Thestreamtubewithaninfinitesimalsectionissaidtobemini-streamtube.Streamlineistheextremecaseofmini-streamtube.截面无穷小的流束。21.Totalflow总流——Totalofcountlessmini-streamtubesiscalledtotalflow.包含流动中所有的微小流束。22.Crosssection(过水断面)---Thesectionisperpendiculartothedirectionoffluidflow.(suchaspipeflowandchannelflow)与流束或总流流线成正交的断面。23.Discharge(流量)---Amountoffluidpassthroughacrosssectionperunittime(suchasthesectioninthechannelorpipe).单位时间内通过某一过水断面的流体体积称为体积流量，简称流量。24.Meanvelocity断面平均流速---Thevelocitiesofpointsonthesamecrosssectioninthetotalflowaredifferent,sousuallyanaveragevelocityisusedinsteadoftherealvelocityoverthecrosssection,thisaveragevelocityiscalledthemeanvelocity.(,,,)(,,,)(,,,)dxdydzuxyztvxyztwxyztdttzyxwdztzyxvdytzyxudx,,,,,,,,,,dAA25.Uniformflow均匀流：isdefinedasuniformflowwhenintheflowfieldthevelocityandotherhydrodynamicparametersdonotchangefrompointtopointatanyinstantoftime(inwhichthecrosssectionofeachstreamtuberemainsunchanged.流场中每一空间点的各运动参数（速度，压力）不随空间位置而变化。26.Nonuniformflow非均匀流：Flowsuchthatthevelocityvariesfromplacetoplaceatanyinstant.27.Steadyflow恒定流：theflowwhosemotionfactorsdon’tchangewithtime.流场中所有的运动要素不随时间变化.28.Unsteadyflow非恒定流：theflowthatatleastoneofitsmotionfactorschangeswithtime.流场中至少有一个运动要素随时间变化