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Author: Vishwas Shringi
Publisher:
ISBN:
Category : Fluid dynamics
Languages : en
Pages :
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Book Description
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.
Author: Vishwas Shringi
Publisher:
ISBN:
Category : Fluid dynamics
Languages : en
Pages :
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Book Description
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.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
This report presents the study of two-equation turbulence modeling. The primary objective of this study is to implement two-equation k-ε and k-ω 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 dem-onstrated 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-ε model contributed by Shih and Lumley and the two-equation k-ω 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-ω model in U2NCLE. Further validation is carried out by comparing computed forces and moments with experi-mental data for the SUBOFF model with sail and stern appendages.
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781720578123
Category :
Languages : en
Pages : 36
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Book Description
USM3D is a widely-used unstructured flow solver for simulating inviscid and viscous flows over complex geometries. The current version (version 5.0) of USM3D, however, does not have advanced turbulence models to accurately simulate complicated flow. We have implemented two modified versions of the original Jones and Launder k-epsilon "two-equation" turbulence model and the Girimaji algebraic Reynolds stress model in USM3D. Tests have been conducted for three flat plate boundary layer cases, a RAE2822 airfoil and an ONERA M6 wing. The results are compared with those from direct numerical simulation, empirical formulae, theoretical results, and the existing Spalart-Allmaras one-equation model.Wang, Qun-Zhen and Massey, Steven J. and Abdol-Hamid, Khaled S.Langley Research CenterAPPLICATIONS PROGRAMS (COMPUTERS); NAVIER-STOKES EQUATION; UNSTRUCTURED GRIDS (MATHEMATICS); TURBULENCE MODELS; AIRFOILS; WINGS; VISCOUS FLOW; FLAT PLATES; INVISCID FLOW; COMPUTERIZED SIMULATION; COMPUTATIONAL FLUID DYNAMICS; K-EPSILON TURBULENCE MODEL; REYNOLDS STRESS; STRESS ANALYSIS; FLOW DISTRIBUTION; FINITE VOLUME METHOD; VORTICES; EDDY VISCOSITY
Author: Tuncer Cebeci
Publisher: Springer Science & Business Media
ISBN: 9783540402886
Category : Science
Languages : en
Pages : 140
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Book Description
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.
Author: Joseph Matthew Jones
Publisher:
ISBN:
Category : Computational fluid dynamics
Languages : en
Pages :
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Book Description
This study reports the development and validation of a modified two-equation eddy-viscosity turbulence model for computational fluid dynamics prediction of transitional and turbulent flows. The existing terms of the standard k-w model have been modified to include transitional flow effects, within the framework of Reynolds-averaged, eddy-viscosity turbulence modeling. The new model has been implemented into the commercially available flow solver FLUENT and the Mississippi State University SimCenter developed flow solver U2NCLE. Test cases included flow over a flat plate, a 2-D circular cylinder in a crossflow, a 3-D cylindrical body and three conical geometries, which represent the nose-cones of aerodynamic vehicles such as missiles. The results illustrate the ability of the model to yield reasonable predictions of transitional flow behavior using a simple modeling framework, including an appropriate response to freestream turbulence quantities, boundary-layer separation, and angle of attack.
Author: G. Kalitzin
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781721997923
Category :
Languages : en
Pages : 36
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Book Description
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...
Author: J. Lee
Publisher:
ISBN:
Category :
Languages : en
Pages : 28
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Book Description
Author: Roger L. Davis
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Institute for Computer Applications in Science and Engineering
Publisher:
ISBN:
Category :
Languages : en
Pages : 36
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