Airfoil Stall Simulations with Algebraic Delayed DES and Physically Based Synthetic Turbulence for RANS-LES Transition

Abstract

For accurate computations of massively separated flows, a variety of Detached Eddy Simulation (DES) approaches have been recently developed. The Algebraic Delayed Detached Eddy Simulation (ADDES) proved to be an efficient approach in performing a reliable switch between RANS and LES regions, thus avoiding Modeled Stress Depletion (MSD). Nevertheless, as with other embedded LES approaches, it requires a large adaptation distance until LES regenerates the physically expected turbulence content, downstream of the RANS-LES interface. In order to shorten this grey area of the embedded LES approaches, a flexible synthetic turbulence generator that can provide a physically realistic velocity field of fluctuations is further developed and applied. The implementation is first tested in a flat plate boundary layer and then for the HGR-01 airfoil at high angles of attack where is validated against experimental data. Results have shown that, applying synthetic turbulence, the generation of turbulent content is effectively accelerated and the resolved turbulence shows good agreement with PIV data. In addition, visualizations and spectral analysis display the physical behavior of turbulence in the LES region.