英文版流体力学.ppt

Fluid Mechanics Lectuer:Sun Gang Introduction 1-2 Definition of a Fluid The solid object will no change inside the a closed container The liquid will change its shape to conform to that of the container and will take on the same boundaries as the container up to the maximum depth of the liquid Fluid mechanics:the behavior of fluids at rest and in motion A fluid is a substance that deforms continuously under the application of a shear(tangential) stress no matter how small the shear stress may be A solid deforms when a shear stress is applied does not continue to increase with the time Dye maker to outline a fluid element Introduction The deformation of solid Experience a Deformation Finite(solid) Continuously increasing Shear stress is proportional To the rate of change of The deformation Introduction 1-4 Basic Equation The ideal gas equation of state The Basic laws governing the flow motion include: 1、The conservation of mass 2、Newton’s second law of motion 3、The principle of angular momentum 4、The first law of theromdynamics 5、The second law of theromdynamics Introduction 1-5 Methods of analysis The system that you are attempting to analyze Basic mechanics : free-body diagram thermodynamics: closed system(terms: system and control volume) 1-5.1 System and Control Volume A system is defined as a fixed, identifiable quantity of mass; the system boundaries separate the system from the surroundings(fixed or movable), no mass crosses the system boundaries. A control volume is an arbitrary volume in space through which fluid flows. The geometric boundary of the comtrol volume is called the control surface.(include real or imaginary) 1-5.2 Differential versus Integral Approach The basic laws can be formulated in terms of infinitesimal or finite systems and control volumes. The first case the resulting equation are differential equation. The integral formulations of basic laws are easier to treat analytically, for der