Intermittency in Turbulent Flows

Abstract

The conception of this book lies somewhere between a proceedings volume and a monograph. It consists of 16 sections on intermittent hydrodynamic or magnetohydrodynamic flow. Each one is written by a different author or team of authors. Each subsection itself offers a review type of presentation, written for this book. It contains many references to recent original work, emphasizing the authors' expertise and contributions. While there is coherence of the presentation, the notions, the symbols, etc, within the subsections, there is hardly any cross-referencing between them, except for the common headline intermittency. The reader finds a rich variety of topics, of building blocks, on the one hand, but on the other hand will miss the unifying view as well as various features and authors he knows to work on intermittent fluid flow. But altogether he gets quite a representative overview on recent progress in this very active field. Some of the articles particularly nicely demonstrate why there is increasing interest in turbulent fluctuations and excitement of researchers about the phenomenon called intermittency. The book is less devoted to applied fluid flow; it concentrates on the physics of intermittency, even in the broader context. A few items treated in this volume should be mentioned in order to provide the reader with appropriate information. These include how to relate the anomalous scaling exponents of the structure functions - the signature of intermittency in fluid flow - with the near-singular flow structures. Are there relations to the often discussed finite time singularities of the Euler equations? The question of universality of intermittent space-time fluctuations in fluid flow in particular and in large classes of nonlinear dynamical systems is dealt with repeatedly. The cascade picture, fractality, multifractality and beyond, are offered. Clearly the mixture of new ideas, notions and conceptions together with discussions and results of many new experiments, also visualization techniques, stimulate the reader's interest and excitement. Competent authors and new material on very recent approaches are the main reasons to recommend this book for researchers in fluid flow and in nonlinear dynamical systems theory, for students as well as for experts. They can find stimulating information on new ideas, for example on multipoint correlators, on the so-called inverted structure functions, on geometrical statistics, etc, and they find this together with less recent material such as on so-called extended self-similarity, on wavelet use etc, and finally on long-standing items. Intermittency is a very vivid, active field. A unified physical understanding is still missing, but a whole host of models, Ans\"atze and experimental findings contribute to the developing nature of this unique phenomenon intermittency. This volume contributes in compiling many details and providing an overview which might lead, in the future, to a summarizing explanation. The reader already looking for that here will be disappointed. Still, it is worthwhile to read or at least look into this book, to experience the dynamics in this field and, perhaps, become engaged by it. Siegfried Grossmann