The flow in the mixing chamber of a supersonic ejector generates two mixing layers between the driving supersonic flow and the entrained subsonic flow. It is those highly turbulent mixing layers that are responsible for the entrainment. The flow was simulated using the Argo code of Cenaero, together with our newly developed wall model validated for subsonic and supersonic flows (to appear in J. Fluid Mechanics). The image shows the density gradient magnitude integrated across the channel width ; which mimics an experimental Schlieren photograph. It reveals the presence of large coherent structures amidst the chaos of turbulence.