Fluid Dynamics and Transport of Droplets and Sprays

Fluid Dynamics and Transport of Droplets and Sprays, by William A. Sirignano, Cambridge University Press, New York, 1999. REVIEWED BY GRETAR TRYGGVASON.

It is easy to make the case for a book on the behavior and properties of sprays. Considerable part of the energy need of mankind is met by burning liquid fuels—almost always by atomizing it first—and other applications are in abundance. Professor Sirignano has contributed in major ways to our current understanding of sprays, both by his own research as well as by his mentoring of many younger spray investigators. In this book, he provides an up-to-date review of modeling of sprays. The book is very much a modeler’s account of spray research and relatively few experimental results are presented or discussed. The book is also heavily—but not exclusively—based on the author’s own research.

The book is divided into nine chapters, of which the first is a short introduction. The combustion of a single drop is then treated in chapters 2 and 3. The emphasis is on models of varying degree of complexity, starting with a discussion of a stationary drop and then adding convective effects. Chapter 2 ends with a short discussion of the effect of radiation and oscillations. Chapter 3 treats drops consisting of multicomponent liquids, metal-slurries, and emulsified fuels. In chapter 4, various ways to account for the presence of many drops and their interactions are examined. Detailed numerical simulations of well-defined problems are used to provide insight and models are developed for practical situations. The chapter ends with a discussion of droplet collisions and collisions of drops with walls. In chapter 5, continuum equations for the evolution of sprays are developed. The spray is treated either in an Eulerian or a Lagrangian way and the equations developed in chapters 2 and 3 serve as subgrid models for unresolved scales. In chapter 6, titled Computational Issues, various ways to solve the equations presented in chapter 5 are discussed. This is perhaps the weakest part of the book. It is apparently based on work done over fifteen years ago and no mention is made of parallelization or multigrid methods, for example. Chapter 6 does, however, contain a very valuable discussion of the accuracy of the point drop approximation. In chapter 7, computations of several complex, yet idealized, situations are presented. The flow is relatively simple and the focus is on the combustion. Only one- or two-dimensional problems are examined. The last two chapters discuss the state-of-the-art of research on droplet interactions with turbulence and vortical structures and droplet behavior at nearcritical, transcritical, and supercritical conditions. Both topics are currently under active study and the reader is provided with a good introduction to the current status and challenges of research in these areas.

Overall the discussion is clear and the material accessible. The author uses either analytical results or fairly detailed numerical simulations to provide the reader with insight, but the ultimate goal is to derive models that can be computed efficiently and used in numerical codes. In a field as rich as sprays, it is impossible to cover everything in a single book and the author has elected to focus on certain topics. A reader looking for experimental data, practical examples, or atomization will have to look elsewhere. Since a number of books treating other aspects of sprays have appeared recently, this is not a problem. My only complaint about the book is that I found the writing somewhat uneven. While the text often flows smoothly, some sections seem to have been completed in a hurry.

The book is certainly a welcome addition to the literature on modeling of sprays. It is a required reading for any student of spray combustion and—at least at the time of this writing—it brings the reader to the state-of-the-art of many aspects of spray research. The book can be used as a textbook for a graduate course on sprays and spray combustion, although it may be necessary to supplement it by more extensive description of atomization and by more examples of practical applications.