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Developments in Water Science, No. 5, Turbulent Jets
Water Research Vol. 12, pp. 203. Pergamon Press 1978. Printed in Great Britain.
BOOK REVIEW Developments in Water Science, No. 5, Turbulent Jets. By N. Rajaratnam. Published by Elsevier, Amsterdam. (1976). Price $37.75. This book is the fifth in the series produced under the advisory editorship of Professor Ven Te Chow of the University of Illinois. The author is from the Department of Civil Engineering at the University of Alberta, Edmonton, Canada. The text includes experimental results obtained from research projects in the Author's Department, as well as a wide, though not exhaustive, range of contemporary data from other sources. The reference list extends to about 150 entries arranged alphabetically. The Preface states that the book 'presents a detailed treatment of the mean flow characteristics of incompressible turbulent jets' and that it 'could be used by graduatestudents in engineering as well as senior undergraduate students and engineers who had a good introductory course in Fluid Mechanics'. Inclusion in the series on 'Developments in Water Science' might perhaps suggest that the book deals with jet and ambient fluids of different density, variously termed forced plumes or buoyant jets in other publications. In fact the discussion is limited to the description of velocity distributions in jets formed in different physical configurations but having the same density as the receiving medium. As indicated in the opening sentence of Chapter 1 the theory is equally applicable to air or water as the fluid medium and data from both fields of research are quoted. The layout of the first three chapters is similar; these deal respectively with the plane turbulent free jet, the circular turbulent jet, and the radial jet, each in a stagnant environment. Each type is defined and the form of velocity profile described as an introduction to the development of the simplified equations of motion and a discussion of dimensional characteristics. The velocity distribution is then obtained independently by both the Tollmein- and Goertler-type solutions. The chapters conclude with illustrated comparisons of various experimental observations. Chapter 4 expands the treatment of plane and circular jets to the case when the receiving fluid is moving in the same direction as the jet; these are described as compound jets. The distributions of velocity at the interface or shear layer between plane jets flowing first over a stagnant receiving layer, and secondly over a compound or moving layer, are developed in Chapter 5 with the appropriate emphasis on the initial mixing region or potential core. Chapter 6 contains a similar treatment of the annular turbulent shear layers formed at the interface of circular jets and stagnant and flowing receiving fluids. Circular shear layers formed by radial jets are discussed only briefly.
The effect of a swirling motion on circular jets is considered before going on to discuss the behaviour of jets which are expanding inside ducts. The latter are referred to as confined jets and include, for example, the situation involved in the operation of jet pumps. The interesting and complex behaviour of jets issuing obliquely and normal to a cross-flowing stream is discussed in Chapter 9. Deflection and deformation of circular jets with the production of counter-rotating vortices are described and illustrated, as well as the penetration of jets into a counterflow. Unfortunately there is no indication of whether the theory necessary to describe the behaviour of buoyant jets issuing obliquely into a cross-flowing stream has yet been developed. The velocity distributions in jets in contact with a boundary, such as would be formed by discharge tangential to a smooth flat plate, are developed in Chapters 10-12. Both simple and compound plane turbulent wall jets are described. A group of axisymmetric wall jets includes radial jets formed by a source located at the wall, the impingement of a circular jet on a large circular plate, and the cylindrical wall jet formed by the insertion of a circular cylinder into a larger concentric circular nozzle. The final chapter deals with a variety of what are termed three-dimensional jets, here defined as those which are neither axisymmetric nor rectangular. Further differentiation is made between three-dimensional jets with two (bluff jets) and three (slender jets) regions of characteristic velocity decay. Slender jets include those formed by rectangular slots and elliptical orifices. Bluff jets are formed by square or nearly square rectangular outlets and the examples include a study of an equilateral triangular jet. The chapter concludes with the treatment of corresponding wall jets. The book is well illustrated with clear diagrams and figures and the mathematical material is carefully presented with considerable attention given to the explanation of the procedural steps used. Although there is no list explaining the sumbols which occur in the text, their significance is defined where they first occur and each chapter is largely self-sufficient in this respect. In his Preface, the Author reviews the coverage of his subject in standard texts on turbulence theory; he concludes that none combines the use of similarity analysis of equations of motion and integral equations and dimensional analysis with the results of carefully chosen experimental d~ita in a comparatively simple treatment. He appears to have fulfilled his claim to provide such a treatise with this addition to the Elsevier series. A. R. AGG
203
BOOK REVIEW Developments in Water Science, No. 5, Turbulent Jets. By N. Rajaratnam. Published by Elsevier, Amsterdam. (1976). Price $37.75. This book is the fifth in the series produced under the advisory editorship of Professor Ven Te Chow of the University of Illinois. The author is from the Department of Civil Engineering at the University of Alberta, Edmonton, Canada. The text includes experimental results obtained from research projects in the Author's Department, as well as a wide, though not exhaustive, range of contemporary data from other sources. The reference list extends to about 150 entries arranged alphabetically. The Preface states that the book 'presents a detailed treatment of the mean flow characteristics of incompressible turbulent jets' and that it 'could be used by graduatestudents in engineering as well as senior undergraduate students and engineers who had a good introductory course in Fluid Mechanics'. Inclusion in the series on 'Developments in Water Science' might perhaps suggest that the book deals with jet and ambient fluids of different density, variously termed forced plumes or buoyant jets in other publications. In fact the discussion is limited to the description of velocity distributions in jets formed in different physical configurations but having the same density as the receiving medium. As indicated in the opening sentence of Chapter 1 the theory is equally applicable to air or water as the fluid medium and data from both fields of research are quoted. The layout of the first three chapters is similar; these deal respectively with the plane turbulent free jet, the circular turbulent jet, and the radial jet, each in a stagnant environment. Each type is defined and the form of velocity profile described as an introduction to the development of the simplified equations of motion and a discussion of dimensional characteristics. The velocity distribution is then obtained independently by both the Tollmein- and Goertler-type solutions. The chapters conclude with illustrated comparisons of various experimental observations. Chapter 4 expands the treatment of plane and circular jets to the case when the receiving fluid is moving in the same direction as the jet; these are described as compound jets. The distributions of velocity at the interface or shear layer between plane jets flowing first over a stagnant receiving layer, and secondly over a compound or moving layer, are developed in Chapter 5 with the appropriate emphasis on the initial mixing region or potential core. Chapter 6 contains a similar treatment of the annular turbulent shear layers formed at the interface of circular jets and stagnant and flowing receiving fluids. Circular shear layers formed by radial jets are discussed only briefly.
The effect of a swirling motion on circular jets is considered before going on to discuss the behaviour of jets which are expanding inside ducts. The latter are referred to as confined jets and include, for example, the situation involved in the operation of jet pumps. The interesting and complex behaviour of jets issuing obliquely and normal to a cross-flowing stream is discussed in Chapter 9. Deflection and deformation of circular jets with the production of counter-rotating vortices are described and illustrated, as well as the penetration of jets into a counterflow. Unfortunately there is no indication of whether the theory necessary to describe the behaviour of buoyant jets issuing obliquely into a cross-flowing stream has yet been developed. The velocity distributions in jets in contact with a boundary, such as would be formed by discharge tangential to a smooth flat plate, are developed in Chapters 10-12. Both simple and compound plane turbulent wall jets are described. A group of axisymmetric wall jets includes radial jets formed by a source located at the wall, the impingement of a circular jet on a large circular plate, and the cylindrical wall jet formed by the insertion of a circular cylinder into a larger concentric circular nozzle. The final chapter deals with a variety of what are termed three-dimensional jets, here defined as those which are neither axisymmetric nor rectangular. Further differentiation is made between three-dimensional jets with two (bluff jets) and three (slender jets) regions of characteristic velocity decay. Slender jets include those formed by rectangular slots and elliptical orifices. Bluff jets are formed by square or nearly square rectangular outlets and the examples include a study of an equilateral triangular jet. The chapter concludes with the treatment of corresponding wall jets. The book is well illustrated with clear diagrams and figures and the mathematical material is carefully presented with considerable attention given to the explanation of the procedural steps used. Although there is no list explaining the sumbols which occur in the text, their significance is defined where they first occur and each chapter is largely self-sufficient in this respect. In his Preface, the Author reviews the coverage of his subject in standard texts on turbulence theory; he concludes that none combines the use of similarity analysis of equations of motion and integral equations and dimensional analysis with the results of carefully chosen experimental d~ita in a comparatively simple treatment. He appears to have fulfilled his claim to provide such a treatise with this addition to the Elsevier series. A. R. AGG
203