A first course in fluid mechanics for civil engineers

Abstract

Book review / Critiques de livres Dr. Gray is presently an Associate Professo in the Department of Civil and Environmental Engineering at West Virginia University at Morgantown in West Virginia. He has considerable experience in teaching fluid mechanics, has published over 100 papers and reports in fluid mechanics, and also has industrial experience. He wrote this text in fluid mechanics for a one-semester course for civil, environmental, and agricultural engineers to provide a narrower focus rather than attempt to cover the whole range of fluid mechanics. Dr. Gray believes that such a narrow focus might motivate the students more readily. This book uses both the US Customary and SI systems of units. This book has 15 chapters and two appendices that deal with Tables of Fluid Properties and Answers to Selected Problems; it also has a Subject Index. The first chapter presents the scope of engineering fluid mechanics — a brief description of many books dealing with fluid mechanics along with a discussion of units. The second chapter treats fluid properties with the discussion of viscosity left to a later chapter. Chapters 3 and 4 present a thorough discussion of the principles of hydrostatics, covering pressure distribution in liquids, manometers, idea of piezometric head, stratified layers, and force exerted on plane surfaces. Discussion of force exerted on curved surfaces and buoyancy is delayed until chapter 14. Chapter 5 presents a discussion of fluid dynamics, starting with the development of the Euler equation along the streamline and its integration to obtain the Bernoulli equation. The author then uses the Bernoulli equation to present and discuss a number of elementary problems like water jets in air, pitot and pitot-static tubes, venturimeter, and sharpcrested weirs. Chapter 5 closes with the development of the Euler equations in the Cartesian system with the Z axis in the vertical direction. Chapter 6 is a rather lengthy presentation of the mass conservation equation. Chapter 7 presents a discussion of viscosity and a detailed derivation of fully developed laminar flor in a circular pipe and ends with a partially complete derivation of the NavierStokes equation in the Cartesian system. Chapter 8 presents a good derivation of the energy equation, which is correctly identified as different from the Bernoulli equation. The idea of the piezometric and total heads is discussed along with some standard problems. Chapter 9 is entitled Pipe Flow 1 and develops the Poiseuille equation using the energy equation and the results derived from chapter 7. It also presents a short discussion of turbulent flow. Chapter 10 presents a brief discussion on dimensional analysis. Pipe Flow 2 constitutes chapter 11, which deals with head loss for turbulent flow in circular pipes, discusses the Moody Diagram, minor losses, and standard pipe flow problems with some comments on turbulent flow in non-circular pipes. The momentum equation is developed in Chapter 12 along with a thorough discussion of a number of problems. Chapter 13 deals with open channel flow. It discusses uniform flow using the Manning equation as well as the friction factor method and nonuniform flow using the idea of the specific head. It also deals with gravity waves including the hydraulic jump. Chapter 15 deals with physical models and similarity. It discusses geometrically similar Reynolds and Froude models as well as some distorted models and ends with brief comments on river models. The treatment of the Euler and Navier-Stokes equations in the Cartesian system could have been made more general by tilting the axes and combining the pressure and body force terms into piezometric gradients. This set of Euler equations could have been integrated to obtain the Bernoulli equation, which would have required the author to present at least a brief treatment of vorticity and potential flow. Further, using the Navier-Stokes equations, the author could have shown how these equations could be simplified to solve a few simple flows, including the Poiseuille equation, in an elegant manner. On the whole, this book is written clearly; it emphasizes engineering relevance, presents numerous worked-out examples, and provides a number of problems for the reader to solve. I think that this book provides a pragmatic introduction to engineering fluid mechanics for students in civil engineering, including environmental and agricultural engineering, and I would recommend this book to them.