Intermediate fluid mechanics

RobertH. Nunn

• Publisher: Routledge
• Year: 2018
• ISBN:
  9781351437479
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Engineering General
• Index: Technology & Engineering

Nunn provides an overview of the topic of fluid mechanics, a subject often considered essential in college engineering programs.

CHAPTER
ONE

BACKGROUND AND INTRODUCTORY MATERIAL

This text is meant to serve as an extension to the many introductory books on fluid mechanics. For this reason the level and nature of the material presented presuppose some understanding on the reader’s part of the fundamental aspects of fluid mechanics. It is the author’s intention to build on this understanding; for those who may feel a bit “rusty” in this regard, a review of one or more of the many excellent texts on the subject is highly recommended. The bibliography at the end of this chapter lists several texts suggested for purposes of review.

Without dwelling on the definition of a fluid, which is assumed to be one of those concepts retained from a first course in fluid mechanics, it may be useful to review what is meant by “mechanics.” Figure 1.1 illustrates this and points out the breadth implied by the general use of the term “mechanics.” In this text we shall not treat the subject of fluid statics except as it comes under discussion as a special case of fluid dynamics, as shown in Fig. 1.1.

To further explain the nature and scope of what follows, Table 1.1 shows some of the major categories into which fluid mechanics has been subdivided over the years.

Whether a particular problem in fluid mechanics falls into one or the other of these categories depends on the relative influence of the two main physical properties defining a fluid: density and viscosity. If the effect of viscosity is negligible (we shall see in some detail what is meant by effect), then the problem may be one in “hydrodynamics.” If the density variations in the flow are dominant, or at least significant, then the methods of compressible flow analysis must be brought to bear. Few problems involving real fluids are totally devoid of the effects of viscosity and variations in density, so the matter is often one requiring a subjective judgment tempered (we always hope) by some knowledge and experience as to what are the important factors in a given flow situation. In fact, many of the most challenging and frustrating problems in fluid mechanics involve flow situations that reside in the “gray areas” that span the categories sho...