Study of a Compression-Ramp Interaction Using Large-Eddy Simulation/Reynolds-Averaged Navier-Stokes Models

Abstract

Two large-eddy simulation/Reynolds-averaged Navier–Stokes models are applied to a shock/boundary interaction generated by a 20 deg compression corner. The models are designed to transition from unsteady Reynolds-averaged Navier–Stokes to large-eddy simulation as the boundary layer shifts from its logarithmic behavior to its wakelike response, but they differ in that one model requires a preselection of a model constant for each problem, while the other computes this constant as a function of local and ensemble-averaged turbulence properties. Predictions are compared with mean-flow and second-moment experimental data obtained at Princeton University. In general, calculatedmean-flow velocity, surface-pressure, and surface skin-friction distributions agree well with the experiment, with the most noticeable discrepancy being a slight overprediction of the level of upstream influence induced by the shock wave. Comparisons with mass-flux fluctuation intensity, Reynolds axial stress, and Reynolds shear-stress profiles are also presented. These show generally good agreement with experimental trends relating to Reynolds stress amplification and anisotropy modulation. The calculations also predict the existence of a low-frequency motion of the separation shock that is probably associated with the motion of the backflow region. Higher-frequency modulations of the shock front as induced by the passage of coherent, streaklike structures through the shock also appear to contribute to the measurable intermittency effects.