A K Epsilson Modeling Of Near Wall Turbulence

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A K Epsilson Modeling Of Near Wall Turbulence

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Author : Z. Yang
language : en
Publisher:
Release Date : 1991

A K Epsilson Modeling Of Near Wall Turbulence written by Z. Yang and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1991 with Turbulence categories.

A New Time Scale Based K Epsilon Model For Near Wall Turbulence

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Author : National Aeronautics and Space Administration (NASA)
language : en
Publisher: Createspace Independent Publishing Platform
Release Date : 2018-06-28

A New Time Scale Based K Epsilon Model For Near Wall Turbulence written by National Aeronautics and Space Administration (NASA) and has been published by Createspace Independent Publishing Platform this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-06-28 with categories.

A k-epsilon model is proposed for wall bonded turbulent flows. In this model, the eddy viscosity is characterized by a turbulent velocity scale and a turbulent time scale. The time scale is bounded from below by the Kolmogorov time scale. The dissipation equation is reformulated using this time scale and no singularity exists at the wall. The damping function used in the eddy viscosity is chosen to be a function of R(sub y) = (k(sup 1/2)y)/v instead of y(+). Hence, the model could be used for flows with separation. The model constants used are the same as in the high Reynolds number standard k-epsilon model. Thus, the proposed model will be also suitable for flows far from the wall. Turbulent channel flows at different Reynolds numbers and turbulent boundary layer flows with and without pressure gradient are calculated. Results show that the model predictions are in good agreement with direct numerical simulation and experimental data. Yang, Z. and Shih, T. H. Glenn Research Center NASA ORDER C-99066-6; RTOP 505-62-21...

A New Time Scale Based K Epsilon Model For Near Wall Turbulence

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Author : National Aeronautics and Space Administration NASA
language : en
Publisher:
Release Date : 2018-10-23

A New Time Scale Based K Epsilon Model For Near Wall Turbulence written by National Aeronautics and Space Administration NASA and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-10-23 with categories.

A k-epsilon model is proposed for wall bonded turbulent flows. In this model, the eddy viscosity is characterized by a turbulent velocity scale and a turbulent time scale. The time scale is bounded from below by the Kolmogorov time scale. The dissipation equation is reformulated using this time scale and no singularity exists at the wall. The damping function used in the eddy viscosity is chosen to be a function of R(sub y) = (k(sup 1/2)y)/v instead of y(+). Hence, the model could be used for flows with separation. The model constants used are the same as in the high Reynolds number standard k-epsilon model. Thus, the proposed model will be also suitable for flows far from the wall. Turbulent channel flows at different Reynolds numbers and turbulent boundary layer flows with and without pressure gradient are calculated. Results show that the model predictions are in good agreement with direct numerical simulation and experimental data. Yang, Z. and Shih, T. H. Glenn Research Center NASA ORDER C-99066-6; RTOP 505-62-21...

An Improved K Epsilon Model For Near Wall Turbulence And Comparison With Direct Numerical Simulation

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Author : T. H. Shih
language : en
Publisher:
Release Date : 1990

An Improved K Epsilon Model For Near Wall Turbulence And Comparison With Direct Numerical Simulation written by T. H. Shih and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1990 with Fluid dynamics categories.

Modeling Of Near Wall Turbulence

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Author : T. H. Shih
language : en
Publisher:
Release Date : 1990

Modeling Of Near Wall Turbulence written by T. H. Shih and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1990 with Turbulence categories.

A Critical Evaluation Of Two Equation Models For Near Wall Turbulence

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Author : National Aeronautics and Space Administration (NASA)
language : en
Publisher: Createspace Independent Publishing Platform
Release Date : 2018-06-27

A Critical Evaluation Of Two Equation Models For Near Wall Turbulence written by National Aeronautics and Space Administration (NASA) and has been published by Createspace Independent Publishing Platform this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-06-27 with categories.

A variety of two-equation turbulence models, including several versions of the K-epsilon model as well as the K-omega model, are analyzed critically for near wall turbulent flows from a theoretical and computational standpoint. It is shown that the K-epsilon model has two major problems associated with it: the lack of natural boundary conditions for the dissipation rate and the appearance of higher-order correlations in the balance of terms for the dissipation rate at the wall. In so far as the former problem is concerned, either physically inconsistent boundary conditions have been used or the boundary conditions for the dissipation rate have been tied to higher-order derivatives of the turbulent kinetic energy which leads to numerical stiffness. The K-omega model can alleviate these problems since the asymptotic behavior of omega is known in more detail and since its near wall balance involves only exact viscous terms. However, the modeled form of the omega equation that is used in the literature is incomplete-an exact viscous term is missing which causes the model to behave in an asymptotically inconsistent manner. By including this viscous term and by introducing new wall damping functions with improved asymptotic behavior, a new K-tau model (where tau is identical with 1/omega is turbulent time scale) is developed. It is demonstrated that this new model is computationally robust and yields improved predictions for turbulent boundary layers. Speziale, Charles G. and Abid, Ridha and Anderson, E. Clay Langley Research Center NAS1-18605..

Parallel Implementation Of A K Epsilon Turbulence Model And Wall Functions For Unstructured Grids

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Author : Thilo Schonfeld
language : en
Publisher:
Release Date : 1996

Parallel Implementation Of A K Epsilon Turbulence Model And Wall Functions For Unstructured Grids written by Thilo Schonfeld and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1996 with categories.

An Improved Near Wall K Epsilon Model For The Calculation Of Wall Bounded Turbulent Flows

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Author : Arup Sarkar
language : en
Publisher:
Release Date : 1995

An Improved Near Wall K Epsilon Model For The Calculation Of Wall Bounded Turbulent Flows written by Arup Sarkar and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995 with Turbulence categories.

A Near Wall Turbulence Model And Its Application To Fully Developed Turbulent Channel And Pipe Flows

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Author : National Aeronautics and Space Administration (NASA)
language : en
Publisher: Createspace Independent Publishing Platform
Release Date : 2018-06-28

A Near Wall Turbulence Model And Its Application To Fully Developed Turbulent Channel And Pipe Flows written by National Aeronautics and Space Administration (NASA) and has been published by Createspace Independent Publishing Platform this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-06-28 with categories.

A near wall turbulence model and its incorporation into a multiple-time-scale turbulence model are presented. In the method, the conservation of mass, momentum, and the turbulent kinetic energy equations are integrated up to the wall; and the energy transfer rate and the dissipation rate inside the near wall layer are obtained from algebraic equations. The algebraic equations for the energy transfer rate and the dissipation rate inside the near wall layer were obtained from a k-equation turbulence model and the near wall analysis. A fully developed turbulent channel flow and fully developed turbulent pipe flows were solved using a finite element method to test the predictive capability of the turbulence model. The computational results compared favorably with experimental data. It is also shown that the present turbulence model could resolve the over shoot phenomena of the turbulent kinetic energy and the dissipation rate in the region very close to the wall. Kim, S.-W. Glenn Research Center NASA ORDER C-99066-G; RTOP 505-62-20...

Progress In Wall Turbulence 2

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Author : Michel Stanislas
language : en
Publisher: Springer
Release Date : 2015-08-17

Progress In Wall Turbulence 2 written by Michel Stanislas and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-08-17 with Technology & Engineering categories.

This is the proceedings of the ERCOFTAC Workshop on Progress in Wall Turbulence: Understanding and Modelling, that was held in Lille, France from June 18 to 20, 2014. The workshop brought together world specialists of near wall turbulence and stimulated exchanges between them around up-to-date theories, experiments, simulations and numerical models. This book contains a coherent collection of recent results on near wall turbulence including theory, new experiments, DNS and modeling with RANS, LES. The fact that both physical understanding and modeling by different approaches are addressed by the best specialists in a single workshop is original.