Explicit algebraic stress models that are valid for three-dimensional turbulent flows in noninertial frames are systematically derived from a hierarchy of second-order closure models. This represents a generalization of the model derived by Pope who based his analysis on the Launder, Reece, and Rodi model restricted to two-dimensional turbulent flows in an inertial frame. The relationship between the new models and traditional algebraic stress models -- as well as anistropic eddy visosity models -- is theoretically established. The need for regularization is demonstrated in an effort to explain why traditional algebraic stress models have failed in complex flows. It is also shown that these explicit algebraic stress models can shed new light on what second-order closure models predict for the equilibrium states of homogeneous turbulent flows and can serve as a useful alternative in practical computations. Gatski, T. B. and Speziale, C. G. Langley Research Center NAS1-18605; NAS1-19480; RTOP 505-90-52-01...
La péface indique : "EUCASS (European Conference for Aero-Space Sciences) is a scientific association at the service of research scientists, engineers, and decision makers active in aeronautical and space sciences. EUCASS, which is an international nonprofit association under the Belgian law, addresses all topics of interest to aerospace, from research challenges to long-term programmes and prospective. It organizes regular conferences, workshops, and meetings. Its goal is to attract the best specialists from Europe and elsewhere, and to create a commonwealth of interest and challenges where in-formation and ideas circulate freely and swiftly, where the currently scattered European knowledge is exchanged much faster and cross-fertilised. EUCASS is the cradle that nurtures a friendly and lively community spirit among all players. It started its activities in 2005 by organizing the first-ever European conference in Moscow, followed at a biennial rate in Brussels and Versailles. In order to contribute to the dissemination of scientific knowledge, we have launched this EUCASS Book Series, the first and second volumes of which were dedicated to Propulsion Physics and presented a selection of the lectures given in Brussels in July 2007. EUCASS is organized in several permanent Technical Committees (TC). One of them is the Flight Physics TC. Within the broad EUCASS framework, the specificc purpose of the Flight Physics TC is to promote the technology, sciences, and arts of Flight physics and to help those engaged in these pursuits to develop their skills and those of their students. This third volume of the EUCASS Book Series on Advances in Aerospace Sciences is dedicated to Flight Physics. It comprises a selected collection of 43 papers presented at the 3rd European Conference for Aerospace Sciences held in Versailles, France, July 06-10, 2009. The current volume is the result of a long review process. About 1/3 of the total number of papers accepted for presentation at the conference was later selected by the volume editors, then edited by an international body of peer reviewers. The volume includes six chapters covering experimental, theoretical and numerical aspects of the fight physics: Chapter One Aerodynamics, Chapter Two Shock Interaction, Chapter Three High Enthalphy Flows, Chapter Four Heat Transfer, Chapter Five Aeroacoustics, Chapter Six Flow Control. To easily identify the material of interest, the reader is invited to consult the brief paper summaries compiled at the start of each chapter."
Turbulence modeling both addresses a fundamental problem in physics, 'the last great unsolved problem of classical physics,' and has far-reaching importance in the solution of difficult practical problems from aeronautical engineering to dynamic meteorology. However, the growth of supercom puter facilities has recently caused an apparent shift in the focus of tur bulence research from modeling to direct numerical simulation (DNS) and large eddy simulation (LES). This shift in emphasis comes at a time when claims are being made in the world around us that scientific analysis itself will shortly be transformed or replaced by a more powerful 'paradigm' based on massive computations and sophisticated visualization. Although this viewpoint has not lacked ar ticulate and influential advocates, these claims can at best only be judged premature. After all, as one computational researcher lamented, 'the com puter only does what I tell it to do, and not what I want it to do. ' In turbulence research, the initial speculation that computational meth ods would replace not only model-based computations but even experimen tal measurements, have not come close to fulfillment. It is becoming clear that computational methods and model development are equal partners in turbulence research: DNS and LES remain valuable tools for suggesting and validating models, while turbulence models continue to be the preferred tool for practical computations. We believed that a symposium which would reaffirm the practical and scientific importance of turbulence modeling was both necessary and timely.
Turbulence modeling both addresses a fundamental problem in physics, 'the last great unsolved problem of classical physics,' and has far-reaching importance in the solution of difficult practical problems from aeronautical engineering to dynamic meteorology. However, the growth of supercom puter facilities has recently caused an apparent shift in the focus of tur bulence research from modeling to direct numerical simulation (DNS) and large eddy simulation (LES). This shift in emphasis comes at a time when claims are being made in the world around us that scientific analysis itself will shortly be transformed or replaced by a more powerful 'paradigm' based on massive computations and sophisticated visualization. Although this viewpoint has not lacked ar ticulate and influential advocates, these claims can at best only be judged premature. After all, as one computational researcher lamented, 'the com puter only does what I tell it to do, and not what I want it to do. ' In turbulence research, the initial speculation that computational meth ods would replace not only model-based computations but even experimen tal measurements, have not come close to fulfillment. It is becoming clear that computational methods and model development are equal partners in turbulence research: DNS and LES remain valuable tools for suggesting and validating models, while turbulence models continue to be the preferred tool for practical computations. We believed that a symposium which would reaffirm the practical and scientific importance of turbulence modeling was both necessary and timely.
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.
The term "turbulence” is used for a large variety of dynamical phenomena of fluids in motion whenever the details of the flow appear to be random and average properties are of primary interest. Just as wide ranging are the theoretical methods that have been applied towards a better understanding of fluid turbulence. In this book a number of these methods are described and applied to a broad range of problems from the transition to turbulence to asymptotic turbulence when the inertial part of the spectrum is fully developed. Statistical as well as nonstatistical treatments are presented, but a complete coverage of the subject is not attempted. The book will be of interest to scientists and engineers who wish to familiarize themselves with modern developments in theories of turbulence. The fact that the properties of turbulent fluid flow are addressed from very different points of view makes this volume rather unique among presently available books on turbulence.
After a brief review of the more popular turbulence models, the author presents and discusses accurate and efficient numerical methods for solving the boundary-layer equations with turbulence models based on algebraic formulas (mixing length, eddy viscosity) or partial-differential transport equations. A computer program employing the Cebeci-Smith model and the k-e model for obtaining the solution of two-dimensional incompressible turbulent flows without separation is discussed in detail and is presented in the accompanying CD.
Most natural and industrial flows are turbulent. The atmosphere and oceans, automobile and aircraft engines, all provide examples of this ubiquitous phenomenon. In recent years, turbulence has become a very lively area of scientific research and application, and this work offers a grounding in the subject of turbulence, developing both the physical insight and the mathematical framework needed to express the theory. Providing a solid foundation in the key topics in turbulence, this valuable reference resource enables the reader to become a knowledgeable developer of predictive tools. This central and broad ranging topic would be of interest to graduate students in a broad range of subjects, including aeronautical and mechanical engineering, applied mathematics and the physical sciences. The accompanying solutions manual to the text also makes this a valuable teaching tool for lecturers and for practising engineers and scientists in computational and experimental and experimental fluid dynamics.
The aim of this series is to publish promptly and in a de- tailed form new material from the field of Numerical Fluid Mechanics including the use of advanced computer systems. Published are reports on specialized conferences, workshops, research programs, and monographs. Contents: This volume contains nineteen reports on work, which is conducted since 1998 in the Collaborative Research Programme "Numerical Flow Simulation" of the Centre National de la Recherche Scientifique (CNRS) and the Deutsche Forschungsgemeinschaft (DFG). French and German engineers and mathematicians present their joint research on the topics "Development of Solution Techniques", "Crystal Growth and Melts", "Flows of Reacting Gases", and "Turbulent Flows". In the background of their work is the still strong growth of the performance of super-computer architectures, which, together with large advances in algorithms, is opening vast new application areas of numerical flow simulation in research and industrial work. Results of this programme from the period 1996 to 1998 have been presented in NNFM 66 (1998)
