Foreword

Most flows encountered in engineering practice are turbulent, and thus it is important to understand how turbulence affects wall shear. However, turbulent flow is a complex mechanism dominated by fluctuation, and despite tremendous amounts of work done in this area by researchers, turbulent flow still is not fully understood. Therefore, we must rely on experiment and the empirical or semi-empirical correlation developed for various situations. In laminar flow, fluid particles flow in an orderly manner along path lines, and momentum and energy are transferred across streamlines by molecular diffusion. In turbulent flow, the swirling eddies transport mass, momentum, and energy to other regions of flow much more rapidly than molecular diffusion, greatly enhancing mass, momentum and heat transfer. As a result, turbulent flow is associated with much higher values of friction, heat transfer, and mass transfer coefficients. The author with his collaboration has been teaching the subject of turbulent flow and the boundary layer for the past twenty years. In addition, this monograph is essential based on the lectures delivered. The lecture notes were prepared to be utilized by the postgraduate student as a part of their research work in the field of mechanical engineering (power generation). Also including about a hundred solved problems that have been given during the courses and examinations. From the experience gained throng useful class discussion and feedback, the notes were revised to improve the clarity and necessary explanatory nots were added during each teaching semester. The subject matter has thus been thoroughly tested in the classroom and found suitable. This book is a compilation and no claim is made of its originality. Acknowledgments are due and hereby made to all the authors whose work has been used in the preparation of this text. Finally, this book emphasizes the need for postgraduate engineers to acquire great efficiency in using the tool of the study and researches in the field of turbulent flow, boundary layers, etc.