Coherent structures in direct numerical simulation of turbulent boundary layers at Mach 3

摘要: We demonstrate that data from direct numerical simulation of turbulent boundary layers at Mach 3 exhibit the same large-scale coherent structures are found in supersonic and subsonic experiments, namely elongated, low-speed features logarithmic region hairpin vortex packets. Contour plots streamwise mass flux show very long low-momentum layer. These carry about one-third kinetic energy. Using Taylor's hypothesis, we find these prevail meander for distances. Structure lengths on order 100 layer thicknesses observed. Length scales obtained correlations severely underpredict extent structures, most likely because their significant meandering spanwise direction. A hairpin-packet-finding algorithm is employed to determine average packet properties, packets similar those observed conditions. connection between wall shear stress Visualization instantaneous turbulence structure shows groups frequently located above structures. This finding consistent with motion model Kim & Adrian (1999).