Turbulence Modelling in Application to The Vortex Shedding of Stalled Airfoils

ABSTRACT A thorough investigation is conducted into some open questions remaining in the Detached–Eddy Simulation (DES) technique. Principle among these are the questions of grid fineness, and the extent of dependency on the background turbulence model inherent in DES. The investigation takes the case of the NACA0012 airfoil beyond stall, for which a large number of grid fineness and turbulence model combinations are computed. In order to investigate the influence of high resolution in the LES zone, a new highly–refined grid is constructed. The results of the investigation demonstrate a strong deterioration of the results due to the uneven grid fineness distribution, and the reasons for this in relation to a general grid sensitivity present in DES are discussed. However, the physical character of the DES calculations remains encouraging, and motivated by this, an analysis of the phenomenon of stochastic weak vortex shedding cycles is undertaken.