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Mechanical Sciences

The Institution of Engineers (India) Text Book Series

by G.K.Lal, Vijay Gupta, N.G.R.Iyengar, B.N.Banerjee and K.Ramesh

1998, Narosa Publishing House, New Delhi

ISBN 81-7319-213-8

This is an introductory book on mechanical engineering fundamentals, viz., solid mechanics, fluid mechanics and thermodynamics and is written keeping in view the syllabus prescribed by The Institution of Engineers (India) for the paper on basics of mechanical engineering. This can equally serve as a good reference book for fresh undergraduate students or practising engineers. In addition to the introductory Chapter, the book consists of 12 chapters devoted to mechanics of solids, six chapters on fluid mechanics and four on thermodynamics spread over 648 pages. The strong point of the book is the considerable amount of emphasis given to explaining the fundamental principles in a clear and lucid manner.

The book begins with a couple of chapters on Force Systems and Equilibrium of Rigid Bodies. Appropriately, the vector approach is used to make equations concise and Free Body Diagrams are emphasized as well as various support conditions. Trusses and Cables are elaborately covered. Students at this level usually do not understand the concept of friction and its application correctly. The book makes special efforts to clarify various aspects of friction and simple machines. The Chapter on particle dynamics is presented systematically including an introduction to vibrations. It is felt that some discussion on rotating frames and a section on rigid body dynamics might enliven students' interest. The Chapter on Stress and Strain and Hooke's Law is kept sufficiently realistic and three-dimensional. The Bending of Beams and Deflections are covered fully. The Elastic Energy concepts and methods are explained in sufficient detail. The Chapters on Fluid Mechanics and Thermodynamics have been well explained.

The presentation is lucid and concise. The accompanying figures are reasonably good. The solved problems should be useful. There are a few printing errors. It would have been better if polymer and food were included in the examples of Non- Newtonian fluids. The important topics such as steam power cycles (e.g., Rankine cycle) and refrigeration cycles should have been discussed. In the discussion on Osborne Reynolds' famous experiment on turbulence it appears as if the celebrated scientist obtained the value of the lower critical Reynolds number for pipe flow (that is, around its well known value of 2000) in his original experiment. The fact is that he obtained the aforesaid value later, when the fluid entering the tube was disturbed. In the original experiment Reynolds used smooth entrance conditions, which gave rise to higher critical Reynolds number (11,800 to 14,300).

The examples are well chosen to explain various aspects of the theories. Interesting problems from day-to-day use have been included. Considering the level of students for whom this is intended, it would have been more appropriate if answers to the problems were also supplied in the book. A new aspect of this introductory book is the inclusion of a bibliography at the end of each Chapter for further reference. Overall this adds to the appreciation of the subject.

N. N. Kishore & P. S. Ghoshdastidar

Computer Simulation of Flow and Heat Transfer

by P.S.Ghoshdastidar

1998, Tata McGraw-Hill Publishing Co. Ltd., New Delhi

ISBN 0-07-463150-0 (Hardcover)

ISBN 0-07-463151-9 (Softcover, with a diskette)

Despite its slightly different title, this book deals with the fundamentals of the ubiquitous Computational Fluid Dynamics (CFD). Indeed, CFD has come of age, and is, undoubtedly here to stay. This field has witnessed remarkable years of progress during the last three decades or so. The large number of specialised journals and conferences, and the books devoted to this subject testify to the phenomenal growth in this field. Nowadays, it is unthinkable to have an undergraduate engineering curriculum without at least one course on CFD. Unfortunately, there are very few good books available at the undergraduate level, and this is where the title under review has a potential to make its mark. Indeed, as claimed by the author, ". . . it is suitable as a text for one semester course at the postgraduate or senior undergraduate level."

There are eight chapters in all. After the introductory material in Chapter 1, the types of partial differential equations and their classifications, encountered in fluid flow and heat transfer are addressed in Chapter 2. A discussion on the related issues of the requisite number of initial and boundary conditions is also included here. Chapter 3 introduces the reader to the various difference expressions, forward, backward and central, for a uniform grid, and central difference expressions for a non-uniform grid. Some advice is also offered on the optimum grid size and how it influences the accuracy of the solution, etc. This is followed by a detailed discussion on the application of finite difference methods for heat conduction in Chapter 4 and for incompressible fluid flow problems in Chapter 5.

At each stage, the author has attempted to offer the best possible advice in the choice of numerical parameters to ensure stability, accuracy and convergence of the solutions. At the same time, merits and demerits of different approaches, e.g., stream function vorticity versus the primitive variables are also presented in respective chapters. Chapter 6 deals with the solution of the convective transport problems in much the same manner as the preceding chapters. The last two chapters deal not only with somewhat advanced and specific applications of CFD, but also where the author himself has contributed to the contemporary research literature. As such these chapters offer a rich collection of problems which can be used in an advanced course.

As stated in the "Preface", the book relates exclusively to the use of finite-difference method, though a terse introduction to the finite element and finite volume methods is provided in Appendix A, whereas the rather short Appendix B briefly describes the oft-used Runge-Kutta method for ODEs. Appendix C presents a computer program (Subroutine TDMA) for solving a system of linear simultaneous equations having tri-diagonal coefficient matrix along with a demonstration program showing its application. Appendix D outlines a methodology to cope with radiation heat transfer problems. The softcover version of the book contains a floppy diskette having computer programs (written in FORTRAN 77) and solutions to some unsolved problems, and solutions [programs] to some typical problems, discussed in the book.

An important feature of the book is the number of illustrations distributed throughout the text to clarify concepts, and equally useful is the number of exercises provided for the reader to tackle. The book is well written and organised and is therefore easy to read. CFD is an area with many pitfalls for the unwary, and I hope this book not only helps the newcomers to the field, but also equips them to avoid some of the hazards!

R. P. Chhabra

WRITING TIPS

Academic writers often face the dilemma of whether or not to include technical terms in their books. Within any subject, the technical terms are more precise and economical than ordinary words. When writing on a technical subject, it may be foolish to try and do without technical terms. This, however, would make the book difficult for students or readers new to the subject. This difficulty may be overcome in two ways: by defining the word the first time it appears in the text, and/or by including a Glossary at the end of the book.

But care must be taken to distinguish between specialised vocabulary used for the sake of scientific accuracy, and jargon used from sheer force of habit. The Prentice-Hall Author's Guide provides an interesting example of the use of jargon: "Generalizations about group behaviour may be structured from a consideration of individualistic attitudinal distinctions." Most readers may not take the trouble to find out what this sentence means!

Authors must keep in mind that it is only the ignorant who confuse pomposity with dignity or unintelligibility with deep learning.

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