Unsteadiness characterisation of shock wave/turbulent boundary-layer interaction at moderate Reynolds number

A direct numerical simulation of an oblique shock wave impinging on a turbulent boundary layer at Mach number 2.28 is carried out moderate Reynolds number, simulating flow conditions similar to those the experiment by Dupont et al. ( J. Fluid Mech. , vol. 559, 2006, pp. 255–277). The low-frequency unsteadiness, whose characteristics have been focus considerable research efforts, here investigated via Morlet wavelet transform. Owing its compact support in both physical and Fourier spaces, transformation makes it possible track time evolution various scales wall-pressure fluctuations. This property also define local intermittency measure, representing frequency-dependent flatness factor, pinpoint bursts energy that characterise scale scale. As major result, decomposition shows broadband movement actually result collection sparse events time, each characterised own temporal feature hidden classical analysis, which can only show time-averaged behaviour. Then, we propose procedure process any relevant series, such as history wall pressure or separation bubble extent, use condition based measure filter content proximity foot isolate intermittent component signal. In addition, analysis reveals behaviour breathing motion recirculation behind reflected shock, allows us detect direct, partial correspondence between most significant region shock.