High-fidelity simulation of shock-wave/boundary layer interactions

We perform direct numerical simulations of impinging shock-boundary layer interaction on a flat plate, in which the shock is not orthogonal to the boundary layer flow. The analysis relies on an idealized configuration, where a spanwise flow component is used to introduce the effect of the sweep angle between a statistically two-dimensional boundary layer and the shock. A quantitative comparison is carried out between the swept case and the corresponding unswept one, and the effect of the domain spanwise width is examined. The analysis reveals that, while the time-averaged swept flow characteristics are basically unaffected by the choice of the domain width, the spectral dynamics of the flow dramatically changes with it. For very narrow domains, a pure two-dimensional, low-frequency component can be detected, which resembles the low-frequency oscillation of the unswept case. The present work is also devoted to compare the performance of Digital Filtering (DF) and Recycling-Rescaling methods (RR) in reaching an equilibrium state for the Direct Numerical Simulation (DNS) of a turbulent boundary layer. We performed two sets of DNS of supersonic and hypersonic boundary layers, based on previous numerical studies. It is found that, overall, the RR method is the most appropriate choice, to quickly reach a correct trend of the wall pressure fluctuations, whereas the DF method is more capable in obtain small deviations of the skin friction coefficient with respect to the benchmark.