2D RANS Mach contours for Reynolds 2.5 × 106 m−1 and Mach 0.5 at the inlet of pulsation frequencies: (a) separated time-step of 50 Hz injection, (b) controlled time-step of 50 Hz injection, (c) 500 Hz injection shedding of separation, and (d) 500 Hz shedding of separation after half a period