Turbulence And Related Phenomena

This book presents some of the most important results concerning atmospheric turbulence and some of its effects on the propagation of a light beam. Atmospheric turbulence causes fluctuations in both the intensity and the phase of the beam and still must be understood and modelized for applications in photonics or environmental metrology. The future of free-space optical (FSO) communication through atmospheric turbulence channels is especially of interest and research on high bit-rate communications attracts more and more interest as an alternative to radio links because of bandwidth, spectrum, and security issues. Some of the current solutions for improving FSO communications are presented in this book.

This book presents some of the most important results concerning atmospheric turbulence and some of its effects on the propagation of a light beam. Atmospheric turbulence causes fluctuations in both the intensity and the phase of the beam and still must be understood and modelized for applications in photonics or environmental metrology. The future of free-space optical (FSO) communication through atmospheric turbulence channels is especially of interest and research on high bit-rate communications attracts more and more interest as an alternative to radio links because of bandwidth, spectrum, and security issues. Some of the current solutions for improving FSO communications are presented in this book.

Turbulence Phenomena provides an introduction to the eddy transfer of momentum, mass, and heat, specifically at interfaces. The approach of the discussion of the subject matter is based on the eddy mixing length concept of Prandtl. Chapter 1 begins with a discussion on basic concepts regarding liquid flow such as viscosity, turbulent flows, and velocities. As concepts and theories are established, the book then discusses the eddy transfer in fluids, specifically eddy transfer of mass and heat within fluids and eddy transfer near solid surfaces. The concept of eddies in different surfaces is discussed in length all throughout numerous chapters. These different surfaces include clean gas-liquid surfaces, clean liquid-liquid interfaces, and film-covered surfaces. The last few chapters focus on the more detailed discussion on turbulence, such as the concept of spontaneous interfacial turbulence and emulsification and turbulent dispersion and coalescence. The book will be of great use to undergraduate students of chemical engineering, physics, and chemistry.

This book critically reexamines what turbulence really is, from a fundamental point of view and based on observations from nature, laboratories, and direct numerical simulations. It includes critical assessments and a comparative analysis of the key developments, their evolution and failures, along with key misconceptions and outdated paradigms. The main emphasis is on conceptual and problematic aspects, physical phenomena, observations, misconceptions and unresolved issues rather than on conventional formalistic aspects, models, etc. Apart from the obvious fundamental importance of turbulent flows, this emphasis stems from the basic premise that without corresponding progress in fundamental aspects there is little chance for progress in applications such as drag reduction, mixing, control and modeling of turbulence. More generally, there is also a desperate need to grasp the physical fundamentals of the technological processes in which turbulence plays a central role.

This book critically reexamines what turbulence really is, from a fundamental point of view and based on observations from nature, laboratories, and direct numerical simulations. It includes critical assessments and a comparative analysis of the key developments, their evolution and failures, along with key misconceptions and outdated paradigms. The main emphasis is on conceptual and problematic aspects, physical phenomena, observations, misconceptions and unresolved issues rather than on conventional formalistic aspects, models, etc. Apart from the obvious fundamental importance of turbulent flows, this emphasis stems from the basic premise that without corresponding progress in fundamental aspects there is little chance for progress in applications such as drag reduction, mixing, control and modeling of turbulence. More generally, there is also a desperate need to grasp the physical fundamentals of the technological processes in which turbulence plays a central role.

The present collection of reprints covers the main contributions of David Ruelle, and coauthors, to the theory of chaos and its applications. Several of the papers reproduced here are classics in the field. Others (that were published in less accessible places) may still surprise the reader. The collection contains mathematical articles relevant to chaos, specific articles on the theory, and articles on applications to hydrodynamical turbulence, chemical oscillations, etc. A sound judgement of the value of techniques and applications is crucial in the interdisciplinary field of chaos. For a critical assessment of what has been achieved in this area, the present volume is an invaluable contribution. Contents:On the Nature of TurbulenceBifurcation in the Presence of a Symmetry GroupThe Ergodic Theory of Axiom A FlowsMicroscopic Fluctuations and TurbulenceStrange AttractorsMeasures Describing a Turbulent FlowDo Turbulent Crystals Exist?Characteristic Exponents for a Viscous Fuid Subjected to Time Dependent ForcesBowen's Formula for the Hausdorff Dimension of Self-Similar SetsErgodic Theory of Chaos and Strange AttractorsLiapunov Exponents from Time SeriesFundamental Limitations for Estimating Dimensions and Lyapunov Exponents in Dynamical SystemsWhere can One Hope to Profitably Apply the Ideas of Chaos? Readership: Nonlinear scientists, researchers in fluid dynamics, mathematical physicists and mathematicians. keywords:Turbulence;Strange Attractor;Chaos;Chemical Oscillation;Ergodic Theory;Turbulent Crystal;Reaction-Diffusion;Hausdorff Dimension;Repeller;Resonance;Recurrence Plot

These proceedings contain the papers presented at the 4th International Symposium on Engineering Turbulence Modelling and Measurements held at Ajaccio, Corsica, France from 24-26 May 1999. It follows three previous conferences on the topic of engineering turbulence modelling and measurements. The purpose of this series of symposia is to provide a forum for presenting and discussing new developments in the area of turbulence modelling and measurements, with particular emphasis on engineering-related problems. Turbulence is still one of the key issues in tackling engineering flow problems. As powerful computers and accurate numerical methods are now available for solving the flow equations, and since engineering applications nearly always involve turbulence effects, the reliability of CFD analysis depends more and more on the performance of the turbulence models. Successful simulation of turbulence requires the understanding of the complex physical phenomena involved and suitable models for describing the turbulent momentum, heat and mass transfer. For the understanding of turbulence phenomena, experiments are indispensable, but they are equally important for providing data for the development and testing of turbulence models and hence for CFD software validation.