Direct Simulation of Surface Roughness Effects with a RANS and DES Approach on Viscous Adaptive Cartesian Grids

Abstract

The main objective of this research is to directly compute the skin friction (cf) and heat transfer (St) coefficients on real rough surfaces using a state-of-the-art unstructured adaptive grid-based finite volume method. Recent experiments with real roughness panels by Bons are computationally simulated in this study. Computational results are compared with experimental data to assess the simulation accuracy. A RANS (Reynolds-Averaged Navier-Stokes) approach based on the Spalart-Allmaras turbulence model and a DES (Detached Eddy Simulation) approach are employed for the computations, and grid refinement studies are conducted to assess the effects of grid resolution. In two cases with rough surfaces, the RANS approach is capable of accurately predicting cf (within 3.5%) while under-predicting St by 8-15%. The DES approach was able to predict cf and St for smooth flat panels but failed in the cases with real roughness. The cause will be further investigated.