A Critical Comparison of Two-Equation Turbulence Models

A Critical Comparison of Two-Equation Turbulence Models
Author: National Aeronautics and Space Adm Nasa
Publisher: Independently Published
Total Pages: 38
Release: 2018-10-21
Genre: Science
ISBN: 9781729047958

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Several two-equation models were proposed and tested against benchmark flows by various researchers. For each study, different numerical methods or codes were used to obtain the results which were reported to be an improvement over other models. However, these comparisons may be overshadowed by the different numerical schemes used to obtain the results. With this in mind, several existing two-equation turbulence models, including k-epsilon, k-tau, k-omega, and q-omega models, are implemented into a common flow solver code for near wall turbulent flows. The quality of each model is based on several criteria, including robustness and accuracy of predicting the turbulent quantities. Lang, N. J. and Shih, T. H. Glenn Research Center NASA ORDER C-99066-G...

Implementation of Two-equation Turbulence Models in U2NCLE

Implementation of Two-equation Turbulence Models in U2NCLE
Author: Vishwas Shringi
Publisher:
Total Pages:
Release: 2001
Genre: Fluid dynamics
ISBN:

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This report presents the study of two-equation turbulence modeling. The primary objective of this study is to implement two-equation k-[epsilon] and k-[omega] turbulence models as a part of the incompressible flow solver, U2NCLE, on unstructured grids. There are several two-equation models but the selection of one which is in par with the model in UNCLE solver is required so that this model can be compared for robustness and accuracy as demonstrated by turbulence models in UNCLE. The selection also requires that the pre-defined arrays and variables can be used to avoid overhead and deviation from the solution procedure used in U2NCLE. The present study deals with the two-equation k-[epsilon] model contributed by Shih and Lumley and the two-equation k-[omega] model contributed by Wilcox. Implementation of these models will give the user multiple options of two-equation turbulence modeling for solution purpose. Particular attention is paid to the efficiency of the implementation. Various approximations to the source terms are considered and the most optimal and accurate approximation is identified. These models are validated via relatively small model problems, for example a flat plate case, by comparing the results with the results obtained from the respective models in UNCLE and the existing two-equation q-[omega] model in U2NCLE. Further validation is carried out by comparing computed forces and moments with experimental data for SUBOFF model with sail and stern appendages.

Turbulence Models and Their Application in Hydraulics

Turbulence Models and Their Application in Hydraulics
Author: Wolfgang Rodi
Publisher: Routledge
Total Pages: 124
Release: 2017-11-01
Genre: Technology & Engineering
ISBN: 1351406574

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This book provides an introduction to the subject of turbulence modelling in a form easy to understand for anybody with a basic background in fluid mechanics, and it summarizes the present state of the art. Individual models are described and examined for the merits and demerits which range from the simple Prandtl mixing length theory to complex second order closure schemes.

Turbulence Models and Their Application in Hydraulics

Turbulence Models and Their Application in Hydraulics
Author: Wolfgang Rodi
Publisher: Ashgate Publishing
Total Pages: 124
Release: 1984
Genre: Science
ISBN:

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This book provides an introduction to the subject of turbulence modelling in a form easy to understand for anybody with a basic background in fluid mechanics, and it summarizes the present state of the art. Individual models are described and examined for the merits and demerits which range from the simple Prandtl mixing length theory to complex second order closure schemes.

Scientific and Technical Aerospace Reports

Scientific and Technical Aerospace Reports
Author:
Publisher:
Total Pages: 602
Release: 1995
Genre: Aeronautics
ISBN:

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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.

Numerical Analysis of Recirculating Ducted Flows

Numerical Analysis of Recirculating Ducted Flows
Author: R. J. Schulz
Publisher:
Total Pages: 40
Release: 1978
Genre: Jets
ISBN:

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A numerical solution procedure for ducted, recirculating flows has been developed and applied to predict both turbulent pipe flow and ducted, coaxial jet mixing with recirculation. The solution procedure is based on a decay-function, finite-difference formulation applied to a system of governing equations based on stream functions and vorticity. The vorticity governing equation is complete in that no source terms have been deleted or neglected in its derivation from the Navier-Stokes equations. Boundary values for all dependent variables are defined by physically realistic conditions. Solutions obtained indicate that the accuracy of the solution procedure depends on having an accurate turbulent viscosity model. (Author).

Turbulent Jets

Turbulent Jets
Author: N. Rajaratnam
Publisher: Elsevier
Total Pages: 315
Release: 1976-01-01
Genre: Science
ISBN: 0080869963

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Turbulent Jets