VORTEX STRUCTURES IN A ROUGH-WALL CHANNEL FLOW AND THEIR INFLUENCE ON PASSIVE SCALAR

摘要

DNSs of turbulent channel Hows with one rough wall and one smooth wall are presented to show how the vorticity field depends on the shape and orientation of the roughness elements. The passive scalar is also evaluated. The high correlation coefficients between vorticity and scalar gradients, in the wall layer, emphasize that in all cases flow visualizations can be used in a laboratory to have a qualitative picture of the modifications of the high- and low-speed streaks. Joint probability density function between vorticity and scalar gradients show how the bursting events affect the scalar distribution.