High-fidelity simulations of discrete roughness boundary-layer transition with added perturbations

Abstract

High-fidelity numerical results have been obtained for low-disturbance wind-tunnel tests of transitional flow including isolated, discrete roughness elements on a 7 deg half-angle cone. Solutions for a range of roughness heights, two angles of attack, and several levels of introduced disturbances were calculated using a wall-resolved high-order, high-fidelity simulation methodology. It was found that the roughness elements did cause transition to turbulence in a manner similar to the experimental data. With no perturbations added, transition occurs downstream of the experimentally observed location. The addition of perturbations moves the transition location forward to more closely match the experimental data, in keeping with trends seen in the wind-tunnel campaign.