Fundamental Concepts in Fluid Mechanics（流体力学中的基本概念）.pdfVIP

A significant portion of these notes summarizes various sections of Massey, but additional material from other sources is also included. Note that the notes are incomplete; they will be completed during the lectures, so please attend Fundamental Concepts in Fluid Mechanics 1. Definition of Fluid Mechanics 2. Fluids 3. Concept of a Continuum 4. Dimensions and Units used in Fluid Mechanics 5. Fluid Properties • Density and Specific Weight • Compressibility • Surface tension • Vapor Pressure • Viscosity 1. DEFINITION OF FLUID MECHANICS Fluid mechanics is that branch of applied mechanics that is concerned with the statics and dynamics of liquids and gases. The analysis of the behaviour of fluids is based upon the fundamental laws of applied mechanics that relate to the conservation of mass, energy and momentum. The subject branches out into sub-disciplines such as aerodynamics, hydraulics, geophysical fluid dynamics and bio-fluid mechanics. 2. FLUIDS A fluid is a substance that may flow. That is, the particles making up the fluid continuously change their positions relative to one another. Fluids do not offer any lasting resistance to the displacement of one layer over another when a shear force is applied. This means that if a fluid is at rest, then no shear forces can exist in it, which is different from solids; solids can resist shear forces while at rest. To summarize, if a shear force is applied to a fluid it will cause flow. Recall the example in class when a book was placed between my hands that were previously moving parallel to one another, even in the presence of the fluid, air. The book was somew