Large-eddy simulation of shock/boundary-layer interaction

This work considers numerical simulations of supersonic flows when shock/turbulent boundary-layer interaction occurs. Such flows reveal the existence of complex mechanisms, which need to be carefully investigated for efficient design of propulsion systems. In this study, large-eddy simulation is used to investigate unsteady mechanisms. Because a shock-capturing scheme is used, a hybrid numerical scheme has been developed to reduce its dissipative properties. The issue of the generation of coherent turbulent inlet boundary conditions is also addressed. To avoid introducing artificial low-frequency modes that could affect the interaction, a method based on a digital-filter approach is used to provide a synthetic-inflow condition over a relatively short distance. The obtained results are analyzed and discussed in terms of mean and turbulent quantities. Excellent agreement between large-eddy simulations and experimental data are obtained for both the undisturbed boundary layer and the shock impingement region. In the latter case, oscillations of the reflected shock occurring at low frequencies are observed, in agreement with previous numerical and experimental findings. Moreover, simulations reveal the presence of such frequencies mainly near the shock foot and within the recirculation bubble. This point gives credit to the hypothesis that the instabilities of the reflected shock are due to the intrinsic low-frequencymovement of the shock/bubble acting dynamically as a coupled system. I