Saleh I., Rabie M.G. Fluid Mechanics for Engineers

Published by Authors, Egypt, 2011. – 173 p. – ISBN: 9789775092007All substances consist of very large number of molecules separated by empty spaces. The intermolecular interaction, depends to a great extent on the interdistance between them. The difference of the properties of solids, liquids and gases depends mainly on their molecular structure. The basic properties of fluids are defined and discussed in this chapter.
In solids, the molecules can be modeled as being held together by tiny springs that permit them to vibrate about their equilibrium position. They, almost, do not exchange positions with other molecules. Solids are almost incompressible and they have, almost, definite volume and shape.
In a liquid, the molecules are also densely packed. They cannot easily escape from one another, but they are free to move with respect to each other. Molecules continually attract and repel one another so that they move in curved, wavy paths rather than straight lines. The attraction force between molecules is sufficient to keep the liquid together in a definite volume. Liquids are of poor compressibility. They have, almost, definite volume but they take the shape of their container and they have a free surface.
In a gas, the molecular activity is very much greater. The space between molecules is large and the intermolecular forces are negligible. The molecules are free to travel away from each other compared with liquids and solids. Therefore, gases occupy their container and they are compressible.
This book is prepared as a basic course in fluid mechanics for engineers, arranged in six chapters.Properties of fluids
Fluid statics
Fluid kinematics
Fluid dynamics
Steady incompressible real flow in hydraulic conduits
Dimensional analysis and similarity