Large-eddy/Reynolds-averaged Navier-Stokes simulation of a Mach 5 compression-corner interaction

Simulations of Mach 5 turbulent How over a 28-deg compression corner are performed using a hybrid large-eddy/Reynolds-averaged Navier-Stokes method. The model captures the mean-flow structure of the interaction reasonably well, with observed deficiencies relating to an underprediction of the displacement effects of the shock-induced separation region. The computational results provide some support for a recent theory concerning the underlying causes of low-frequency shock-wave oscillation. In the simulations, the sustained presence of a collection of streaks of fluid with lower/higher momentum than the average induces a low-frequency undulation of the separation front. Power spectra obtained at different streamwise stations are in good agreement with experimental results. Downstream of reattachment, the simulations capture a three-dimensional mean-flow structure, dominated by counter-rotating vortices that produce wide variations in the surface skin friction. Predictions of the structure of the reattaching boundary layer agree well with experimental pitot pressure measurements. In comparison with Reynolds-averaged model predictions, the hybrid large-eddy/Reynolds-averaged Navier-Stokes model predicts more amplification of the Reynolds stresses and a broadening of the Reynolds stress distribution within the boundary layer that is probably due to reattachment-shock motion.