An Introduction to Fluid Mechanics - Importance of Fluid mechanics for Physicist and Engineers

What is Fluid Mechanics an introduction

Fluid mechanics deals with the flow of fluids. Its study is important to physicists, whose main interest is in understanding phenomena. They may, for example, be interested in learning what causes the various types of wave phenomena in the atmosphere and in the ocean, why a layer of fluid heated from below breaks up into cellular patterns, why a tennis ball hit with “top spin” dips rather sharply, how fish swim, and how birds fly.

Importance of Fluid mechanics for Physicist and Engineers

The study or fluid mechanics is just as important to engineers, whose main interest is in the applications of fluid mechanics to solve industrial problems. Aerospace engineers may be interested in designing airplanes that have low resistance and, at the same time, high “lift” force to support the weight of the plane. Civil engineers may be interested in designing irrigation canals, dams, and water supply systems. Pollution control engineers may be interested in saving our planet from the constant dumping of industrial sewage into the atmosphere and the ocean. Mechanical engineers may be interested in designing turbines, heat exchangers, and fluid cooling. Chemical engineers may be interested in designing efficient devices to mix industrial chemicals. The objectives of physicists and engineers, however, are not quite separable because the engineers need to understand and the physicists need to be motivated through applications. Fluid mechanics, like the study of any other branch of science, needs mathematical analyses as well as experimentation. The analytical approaches help in finding the solutions to certain idealized and simplified problems, and in understanding the unity behind apparently dissimilar phenomena. Needless to say, drastic simplifications are frequently necessary because of the complexity of real phenomena. A good under-standing of mathematical techniques is definitely helpful here, although it is probably fair to say that some of the greatest theoretical contributions have come from the people who depended rather strongly on their unusual physical intuition, some sort of a “vision” by which they were able to distinguish between what is relevant and what is not. Chess player, Bobby Fischer (appearing on the television program “The Johy Carson Show,” about 1979), once compared a good chess player and a pat one in the following manner: When a good chess player looks at a chess board, he thinks of 20 possible moves; he analyzes all of them and picks the one that he likes. A great chess player, on the other hand, analyzes only two or three possible moves; his unusual intuition (part of which must have grown from experience) allows him immediately to rule out a large number of moves without going through an apparent logical analysis. Ludwig Prandtl, one of the founders of modem fluid mechanics, first conceived the idea of a boundary layer based solely on physical intuition. His knowledge of mathematics was rather limited, as his famous student Von Kannan testifies. Interestingly, the boundary layer technique has now become one of the most powerful methods in applied mathematics! As in other fields, our mathematical ability is too limited to tackle the complex problems of real fluid flows. Whether we are primarily interested either in under- standing the physics or in the applications, we must depend heavily on experimental observations to test our analyses and develop insights into the nature of the phenomenon. Fluid dynamists cannot afford to think like pure mathematicians. The well-known English pure mathematician G. H. Hardy once described applied mathematics as a form of “glorified plumbing” (G. I. Taylor, 1974). It is frightening to imagine what Hardy would have said of experimental sciences!

This article is an introduction to fluid mechanics, and is aimed at both physicists and engineers. While the emphasis is on understanding the elementary concepts involved, applications to the various engineering fields will be discussed so as to motivate the reader whose main interest is to solve industrial problems. Needless to say, the reader Will not get complete satisfaction even after reading the entire article.

It is more likely that he or she will have many questions about the nature of fluid flows than before studying this article. The purpose of the article, however, will be well served if the reader is more curious and interested in fluid flows.

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