A VERY low temperature (like 100 K) air flow at high velocities (400 m/s - mach number around 2, static pressure = 34440 Pa) is being discharged into the ambient atmosphere (300 K, static pressure 1E5 Pa) through a converging-diverging nozzle. Flow separation will take place due to oblique shock waves. My question is how far can the flow separation go? Will it exceed even the throat? If the same air is being exhausted at much lower speed (100m/s - mach number around 0.5, static pressure = 34440 Pa), what will happen. Will the air refuse to go out or will a gradual temperature gradient form after the flow becomes steady.