… Photograph (top) of the analogy to shock cells downstream of a nozzle at Mach number
1.35, with flow from left to right. The text below the water flow is used as a reference for
surface reconstruction; time-averaged surface (bottom) topography of the shock cells of the
same flow, the contours indicate the surface gradient in the flow direction, increasing from
blue to red (negative to positive). The reconstructed surface from the reference image
topography technique matches well with the real free surface flow …