文档介绍：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
At the atomic and molecular level:
Solid:the molecular are packed so closely together that their nuclei and electrons form a rigid geometric structure,”glued”together by powerful intermolecular forces.
Liquid:the space between molecular is large,the intermolecular forces allow enough movement of the molecules to give the liquid its “fluidity”
Gas:the spacing between molecular is much larger, the influence of the intermolecular forces is much weaker,and the motion of the molecules occurs rather freely throughout the gas
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- 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 cross