Title

Implementation and validation of a modified non-equilibrium Wilcox k omega turbulence model in subsonic and transonic flow regimes

Date of Award

2013

Degree Name

M.S. in Aerospace Engineering

Department

Department of Mechanical and Aerospace Engineering

Advisor/Chair

Advisor: Markus P. Rumpfkeil

Abstract

Large Eddy Simulations (LES) are beginning to emerge as the state-of-the art for turbulence modeling in Computational Fluid Dynamics (CFD), but due to current computational constraints, the need will continue to exist for a lower fidelity, yet robust set of Reynolds-Averaged Navier- Stokes (RANS) turbulence models. Many of these turbulence models are based off of the classic Boussinesq approximation which relates the mean flow stresses to the turbulent eddy viscosity. The traditional Boussinesq approximation relies upon the instantaneous strain rate which may produce large errors in solutions for flows with significant changes in strain (such as areas of massive separation and re-attachment). The unstructured Navier-Stokes solver AVUS is modified using a new method developed by Peter E. Hamlington and Werner J. A. Dahm which replaces the classic Boussinesq approximation with a new non-equilibrium closure technique. The new non-equilibrium k omega turbulence model modification takes into account the time history of the strain rate by modifying the eddy viscosity term found in the k omega Wilcox turbulence model. Computational results from this new model are compared to experimental data from numerous test cases which include a two-dimensional flat plate, NACA 0012 airfoil, RAE 2822 transonic airfoil, and a fully three-dimensional unmanned aerial vehicle. The results of the new model are encouraging since they are more closely correlating to experimental data.

Keywords

Turbulence Mathematical models, Eddies Viscosity Mathematical models, Fluid dynamics Approximation methods, Aerospace engineering; Hamlington and Dahm; turbulence; turbulence modeling; RANS; non-equilibrium turbulence modeling

Rights Statement

Copyright © 2013, author

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