Zonal-detached-eddy simulation of the flow around a high-lift configuration

A zonal hybrid Reynolds-averaged Navier-Stokes large-eddy simulation (RANS/LES) approach, called zonal-DES, used to handle a two-dimensional high-lift configuration with deployed slat and flap is presented. This method allows to reduce significantly the cost of an accurate numerical prediction of the unsteady flow around wings compared to a complete LES. Some issues concerning grid generation as well as the use of zonal-detached-eddy simulation for a multi-element airfoil are discussed. The basic planar grid has 250,000 points and the finest spanwise grid has 31 points with Delta z/c = 0.002. The effort is geared toward detailed comparison of the numerical results with the Europiv2 experimental particle image velocimetry data including both mean and fluctuating properties of the velocity field (Arnott, A., Neitzke, K. P., Agocs, J., Sammer, G., Schneider, G., and Schroeder, A., Detailed Characterisation Using PIV of the Flow Around an Aerofoil in High Lift Configuration, EUROPIV2 Workshop on Particle Image Velocimetry, Springer, Berlin, 2003). The results also provide an insight into the real unsteady nature of the flow around a three-element airfoil that cannot be reproduced by classical RANS models. The current calculation displays extremely complex flow dynamics in the slat and flap coves like the ejection process through the gaps oiseveral vortices issued from the impingement of the free shear layers on the lower walls of the different elements.