New Results on the Realizability of Reynolds Stress Turbulence Closures
| Author | : Institute for Computer Applications in Science and Engineering |
| Publisher | : |
| Total Pages | : 56 |
| Release | : 1993 |
| Genre | : |
| ISBN | : |
On The Realizability Of Reynolds Stress Turbulence Closures
Download On The Realizability Of Reynolds Stress Turbulence Closures full books in PDF, epub, and Kindle. Read online free On The Realizability Of Reynolds Stress Turbulence Closures ebook anywhere anytime directly on your device. Fast Download speed and no annoying ads. We cannot guarantee that every ebooks is available!
New Results on the Realizability of Reynolds Stress Turbulence Closures
| Author | : National Aeronautics and Space Adm Nasa |
| Publisher | : |
| Total Pages | : 56 |
| Release | : 2018-10-29 |
| Genre | : Science |
| ISBN | : 9781729389782 |
The realizability of Reynolds stress models in homogeneous turbulence is critically assessed from a theoretical standpoint. It is proven that a well known second-order closure formulated by Shih and Lumley using the strong realizability constraints of Schumann is, in fact, not a realizable model. The problem arises from the failure to properly satisfy the necessary positive second time derivative constraint when a principal Reynolds stress vanishes - a fatal flaw that becomes apparent when the non-analytic terms in their model are made single-valued as required on physical grounds. It is furthermore shown that the centrifugal acceleration generated by rotations of the principal axes of the Reynolds stress tensor can make the second derivative singular at the most extreme limits of realizable turbulence. This previously overlooked effect appears to make it impossible to identically satisfy the strong form of realizability in any version of the present generation of second-order closures. On the other hand, models properly formulated to satisfy the weak form of realizability - wherein states of one or two component turbulence are not accessible in finite time are found to be realizable. However, unlike the simpler and more commonly used second order closures, these models can be ill-behaved near the extreme limits of realizable turbulence due to the way that higher-degree nonlinearities are often unnecessarily introduced to satisfy realizability. Illustrative computations of homogeneous shear flows are presented to demonstrate these points which can have important implications for turbulence modeling. Speziale, Charles G. and Abid, Ridha and Durbin, Paul A. Langley Research Center...
A Realizable Reynolds Stress Algebraic Equation Model
| Author | : Tsan-Hsing Shih |
| Publisher | : |
| Total Pages | : 40 |
| Release | : 1993 |
| Genre | : Reynolds stress |
| ISBN | : |
The invariance theory in continuum mechanics is applied to analyze Reynolds stresses in high Reynolds number turbulent flows. The analysis leads to a turbulent constitutive relation that relates the Reynolds stresses to the mean velocity gradients in a more general form in which the classical isotropic eddy viscosity model is just the linear approximation of the general form. On the basis of realizability analysis, a set of model coefficients are obtained which are functions of the time scale ratios of the turbulence to the mean strain rate and the mean rotation rate. The coefficients will ensure the positivity of each component of the mean rotation rate. These coefficients will ensure the positivity of each component of the turbulent kinetic energy - realizability that most existing turbulence models fail to satisfy. Separated flows over backward-facing step configurations are taken as applications. The calculations are performed with a conservative finite-volume method. Grid-independent and numerical diffusion-free solutions are obtained by using differencing schemes of second-order accuracy on sufficiently fine grids. The calculated results are compared in detail with the experimental data for both mean and turbulent quantities. The comparison shows that the present proposal significantly improves the predictive capability of K-epsilon based two equation models. In addition, the proposed model is able to simulate rotational homogeneous shear flows with large rotation rates which all conventional eddy viscosity models fail to simulate.
Dynamics of Nonlinear Stochastic Systems
| Author | : R H Kraichnan |
| Publisher | : Legare Street Press |
| Total Pages | : 0 |
| Release | : 2023-07-18 |
| Genre | : |
| ISBN | : 9781019568965 |
In this classic of chaos theory, the late physicist R. H. Kraichnan explores the dynamics of nonlinear stochastic systems. From the mathematics of turbulence to the intricacies of fluid dynamics, Kraichnan's book is a tour-de-force of applied mathematics and physics. Whether you are a researcher, engineer, or mathematician, Dynamics of Nonlinear Stochastic Systems is an essential reference. This work has been selected by scholars as being culturally important, and is part of the knowledge base of civilization as we know it. This work is in the "public domain in the United States of America, and possibly other nations. Within the United States, you may freely copy and distribute this work, as no entity (individual or corporate) has a copyright on the body of the work. Scholars believe, and we concur, that this work is important enough to be preserved, reproduced, and made generally available to the public. We appreciate your support of the preservation process, and thank you for being an important part of keeping this knowledge alive and relevant.
Universal Realizable Anisotropic Prestress Closure for the Normalized Reynolds Stress
| Author | : Karuna Sree Koppula |
| Publisher | : |
| Total Pages | : 630 |
| Release | : 2009 |
| Genre | : Integral closure |
| ISBN | : |
Scientific and Technical Aerospace Reports
| Author | : |
| Publisher | : |
| Total Pages | : 700 |
| Release | : 1995 |
| Genre | : Aeronautics |
| ISBN | : |
Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Turbulent Fluid Flow
| Author | : Peter S. Bernard |
| Publisher | : John Wiley & Sons |
| Total Pages | : 356 |
| Release | : 2019-03-11 |
| Genre | : Science |
| ISBN | : 1119106222 |
A guide to the essential information needed to model and compute turbulent flows and interpret experiments and numerical simulations Turbulent Fluid Flow offers an authoritative resource to the theories and models encountered in the field of turbulent flow. In this book, the author – a noted expert on the subject – creates a complete picture of the essential information needed for engineers and scientists to carry out turbulent flow studies. This important guide puts the focus on the essential aspects of the subject – including modeling, simulation and the interpretation of experimental data - that fit into the basic needs of engineers that work with turbulent flows in technological design and innovation. Turbulent Fluid Flow offers the basic information that underpins the most recent models and techniques that are currently used to solve turbulent flow challenges. The book provides careful explanations, many supporting figures and detailed mathematical calculations that enable the reader to derive a clear understanding of turbulent fluid flow. This vital resource: Offers a clear explanation to the models and techniques currently used to solve turbulent flow problems Provides an up-to-date account of recent experimental and numerical studies probing the physics of canonical turbulent flows Gives a self-contained treatment of the essential topics in the field of turbulence Puts the focus on the connection between the subject matter and the goals of fluids engineering Comes with a detailed syllabus and a solutions manual containing MATLAB codes, available on a password-protected companion website Written for fluids engineers, physicists, applied mathematicians and graduate students in mechanical, aerospace and civil engineering, Turbulent Fluid Flow contains an authoritative resource to the information needed to interpret experiments and carry out turbulent flow studies.
Theories of Turbulence
| Author | : Martin Oberlack |
| Publisher | : Springer |
| Total Pages | : 377 |
| Release | : 2014-05-04 |
| Genre | : Science |
| ISBN | : 3709125642 |
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.
Handbook of Fluid Dynamics
| Author | : Richard W. Johnson |
| Publisher | : CRC Press |
| Total Pages | : 1544 |
| Release | : 2016-04-06 |
| Genre | : Science |
| ISBN | : 1439849579 |
Handbook of Fluid Dynamics offers balanced coverage of the three traditional areas of fluid dynamics—theoretical, computational, and experimental—complete with valuable appendices presenting the mathematics of fluid dynamics, tables of dimensionless numbers, and tables of the properties of gases and vapors. Each chapter introduces a different fluid dynamics topic, discusses the pertinent issues, outlines proven techniques for addressing those issues, and supplies useful references for further research. Covering all major aspects of classical and modern fluid dynamics, this fully updated Second Edition: Reflects the latest fluid dynamics research and engineering applications Includes new sections on emerging fields, most notably micro- and nanofluidics Surveys the range of numerical and computational methods used in fluid dynamics analysis and design Expands the scope of a number of contemporary topics by incorporating new experimental methods, more numerical approaches, and additional areas for the application of fluid dynamics Handbook of Fluid Dynamics, Second Edition provides an indispensable resource for professionals entering the field of fluid dynamics. The book also enables experts specialized in areas outside fluid dynamics to become familiar with the field.
