Statistical Analysis of Coherent Vortical Structures in a Supersonic Turbulent Boundary Layer

coherent vortical structures in a compressible turbulent boundary layer are statistically analyzed by means of direct numerical simulation of the compressible Navier–Stokes equations for Mach number M=2 and Reynolds number Re_θ≈1000 based on the inlet momentum thickness. It is found that a large variety of hairpin-like and cane-like vortical structures exist in the boundary layer and the most popular structure is the cane-like one. The injection and sweep events contribute a major proportion of the total Reynolds stress. This study indicates structural similarities with the incompressible case. Moreover, the length scales of coherent structures in the streamwise and spanwise directions increase with the distance from the wall. The inclination angle of coherent vortical structures with respect to the streamwise direction increases from the sublayer to the buffer layer and then decreases from the buffer layer to the wake region.