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DIFFERENTIAL EQUATION BASED LENGTH SCALE EVALUATIONS FOR DES, RANS AND MOVING GRID SOLUTIONS

Paul G. Tucker
Fluid Dynamics Research Centre, School of Engineering, The University of Warwick, Coventry; Whittle laboratory, University of Cambridge, UK

Sinopsis

Surprisingly expensive to compute wall distances are still used in a range of key turbulence models. Potentially economical, accuracy improving differential equation based distance algorithms are described. These involve an elliptic Poisson and a hyperbolic natured Eikonal equation approach. Eikonal extension to a Hamilton-Jacob equation is discussed. Use of this to improve turbulence model accuracy and, along with the Eikonal, enhance Detached Eddy Simulation (DES) techniques is considered. Although less accurate than the Eikonal, Poisson method based flow solutions are extremely close to those using a search procedure. For a moving grid case the Poisson method is found especially efficient. Results show that with care the Eikonal equation can be solved on highly stretched, non-orthogonal, curvilinear grids.