Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 26
Book Description
Implementation of a Two-Equation K-omega Turbulence Model in NPARC
Author: Implementation of a Two-equation K-[omega] Turbulence Model in NPARC
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Author: Dennis Yoder (A.)Implementation of a Two-equation K-w Turbulence Model in NPARC
Author: Dennis A. YoderModification of the Two-equation Turbulence Model in NPARC to a Chien Low Reynolds Number K-epsilon Formulation
Author: Nicholas J. GeorgiadisPublisher:
ISBN:
Category : K-Epsilon turbulence model
Languages : en
Pages :
Book Description
This report documents the changes that were made to the two-equation k-epsilon turbulence model in the NPARC (National-PARC) code. The previous model based on the low Reynolds number model of Speziale, was replaced with the low Reynolds number k-epsilon model of Chien. The most significant difference was in the turbulent Prandtl numbers appearing in the diffusion terms of the k and epsilon transport equations. A new inflow boundary condition and stability enhancements were also implemented into the turbulence model within NPARC. The report provides the rationale for making the change to the Chien model, code modifications required, and comparisons of the performances of the new model with the previous k-epsilon model and algebraic models used most often in PARC/NPARC. The comparisons show that the Chien k-epsilon model installed here improves the capability of NPARC to calculate turbulent flows.
Modification of the Two-equation Turbulence Model in NPARC to a Chien Low Reynolds Number K-e Formulation
Author: Nicholas J. GeorgiadisPublisher:
ISBN:
Category : Turbulence
Languages : en
Pages : 22
Book Description
An NPARC Turbulence Module with Wall Functions
Author: J. ZhuImproved Two-equation K-omega Turbulence Models for Aerodynamic Flows
Author: Implementation of Two-equation Turbulence Models in U2NCLE
Author: Vishwas ShringiPublisher:
ISBN:
Category : Fluid dynamics
Languages : en
Pages :
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.
International Aerospace Abstracts
Author: Improved Two-Equation K-Omega Turbulence Models for Aerodynamic Flows
Author: National Aeronautics and Space Adm NasaPublisher:
ISBN: 9781728958446
Category :
Languages : en
Pages : 38
Book Description
Two new versions of the k-omega two-equation turbulence model will be presented. The new Baseline (BSL) model is designed to give results similar to those of the original k-omega model of Wilcox, but without its strong dependency on arbitrary freestream values. The BSL model is identical to the Wilcox model in the inner 50 percent of the boundary-layer but changes gradually to the high Reynolds number Jones-Launder k-epsilon model (in a k-omega formulation) towards the boundary-layer edge. The new model is also virtually identical to the Jones-Lauder model for free shear layers. The second version of the model is called Shear-Stress Transport (SST) model. It is based on the BSL model, but has the additional ability to account for the transport of the principal shear stress in adverse pressure gradient boundary-layers. The model is based on Bradshaw's assumption that the principal shear stress is proportional to the turbulent kinetic energy, which is introduced into the definition of the eddy-viscosity. Both models are tested for a large number of different flowfields. The results of the BSL model are similar to those of the original k-omega model, but without the undesirable freestream dependency. The predictions of the SST model are also independent of the freestream values and show excellent agreement with experimental data for adverse pressure gradient boundary-layer flows. Menter, Florian R. Ames Research Center RTOP 505-59-40...