流体力学(英文资料)PPT文件格式下载.ppt

1、Fluid MechanicsFrank M.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%final exam,Contents Chapter 1Introduction（6 hours）Chapter 2Fluid Statics（4 hours）Chapter 3Integral Relations（12 hours）Chapter 4Differential Relations（8 hours）Chapter 5Boundary Layer（6 hours）Chap

2、ter 6Flow Compressibility（2 hours）Chapter 7Vorticity（4 hours）Summary（2 hours）,Chapter 1 Introduction,1.1 Preliminary Remarks When you think about it,almost everything on this planet either is a fluid or moves within or near a fluid.-Frank M.White,Some examples,Jupiter,Human plume,Wing tip vortex,Tor

3、nado,A3807379.8 24.2（m）,An-225 8488.418.1（m）,A turbofan（涡扇）jet engine,；,CFM56 in MTU,What is Fluid Mechanics?,Fluid Mechanics is the study of fluid either in motion（Fluid Dynamics 流体动力学）or at rest（Fluid Statics 流体静力学）and subsequent effects of the fluid upon the boundaries,which may be either solid s

4、urfaces or interfaces with other fluids.,What is afluid?,The concept of a fluid,A solid can resist a shear stress（剪切应力）by a static deformation.A fluid can not resist a shear stress by a static deformation.Any shear stress applied to a fluid,no matter how small,will result in motion of that fluid.The

5、 fluid moves and deforms continuously as long as the shear is applied.,History and Scope of Fluid Mechanics,Pre-history:Sailing ships with oars（橹桨）and irrigation system were both known in prehistory,Archimedes（285-212 BC）,Parallelogram law for addition of vectors Law of buoyancy,曹冲（196-208）,Leonardo

6、 da Vinci（1452-1519）,Equation of conservation of mass in one-dimensional steady flow Experimentalist Turbulence,Isaac Newton（1642-1727）,Laws of motion Laws of viscosity of Newtonian fluid,18th century,Mathematicians：,Euler（欧拉）：Euler equationBernoulli（伯努利）：Bernoulli equation,Ideal flow solutions,DAle

7、mbert（达朗贝尔）：DAlembert paradox（佯谬，疑题）,Engineers：Hydraulics（水力学）relaying on experiment,Channels，Ship resistance，Pipe flows,Pitot Venturi Torricelli Poiseuille,19th century,Navier（1785-1836）&Stokes（1819-1905）N-S equation,Reynolds（1842-1912）TurbulenceFamous experiment on transition Reynolds Number,20th

8、century,Ludwig Prandtl（1875-1953）,钱学森（1911-2009）,陆士嘉（1911-1986）,Boundary layer theory（1904）To be the single most important tool in modern flow analysis.,The father of modern fluid mechanics,Von Karman（1881-1963）,1.2 Some Properties of fluids,（1）.viscosity（粘性）*Definition：When a fluid is sheared（剪切）,i

9、t begins to move.Subsequently,a pair of forces appear on the shear surface,which resists the shear motion of the fluid.This is called viscosity.,*The nature of viscosity：,For liquid it is cohesion（结合）（oil_00100.mov）,For gas it is the transport of momentum（动量输运）（Particle_flow.mov）,Velocity gradient,*

10、Newtonian law of viscosity（牛顿粘性定律，牛顿内摩擦定律）,Shear stress,The velocity gradient is comparable to deformation.,This kind of linear fluid is called Newtonian fluid.（牛顿流体）,Real fluid（Viscous）,Ideal fluid（Inviscid&Frictionless）,For certain fluid,m is function of temperature.（liquids,gases）,m:Coefficient o

11、f viscosity Dynamic coefficient of viscosity（动力粘性系数）N s/m2,n=m/r:Kinematic coefficient of viscosity（运动粘性系数）m2/s,（2）.Compressibility（压缩性）,Incompressible（不可压）:r=constMost liquid flows are treated as incompressible.Only 1%increase if pressure increase by 220,Compressible（可压缩）:r=r（P,T）Gases can also be

12、treated as incompressible when their velocity is less than 0.3 Ma numbers,（3）.State Relations for Gases Perfect-gas Law（理想气体状态方程）,Ernst Mach,R=287.06 for air,（4）.Thermal Conductivity（热传导）,:heat flux in n direction per unit areak:coefficient of thermal conductivityT:temperature n:direction of heat tr

13、ansfer,Fouriers law of heat conduction,1.3 The Fluid as a Continuum（连续介质）,Density（密度）,Elemental volume（流体微团、流体质点）Large enough in microscope（微观）10-9mm3 of air at standard conditions contains approximately 3107 molecules.,Most engineering problems are concerned with physical dimensions much larger tha

14、n this limiting volume.,Such a fluid is called a continuum,which simply means that its variation in properties is so smooth that the differential calculus can be used to analyze the substance.,*Small enough in macroscope（宏观）.,微观无穷大宏观无穷小,So density is essentially a point function and fluid properties

15、 can be thought of as varying continually in space.,1.4 Surface force（表面力）and body force（质量力，体积力）,Surface forces act continuously on the side surfaces of fluid elements.Pressure,friction.Contact surface force per unit area（单位面积）（应力）,Body forces act on the entire mass of the element.Gravity,electroma

16、gnetic.No cotactPer unit mass（单位质量）g,1.5 Two different points of view in analyzing problems in mechanics,*The Eulerian view（欧拉观点）and the Lagrangian view（拉格朗日观点）The Eulerian view is concerned with the field of flow,appropriate to fluid mechanics.,The Lagrangian view follows an individual particle moving through the flow,appropriate to solid mechanics.,The contrast of two frames,*Flow classification（流动分类）,Ac