Comparison and Scaling of the Bursting Period in Rough and Smooth Walls Channel Flows

Abstract

The Structure of Smooth and k-type rough wall turbulent channel flows was examined over a Reynolds number range of 12,700–55,000 using a few of the most common detection techniques (Modified U_Level (MODUL), TERA, Quadrant analysis) and conditional averages. When grouping time is used and a threshold-independent range could be found, all of the above techniques yield approximately the same time between bursts in the major part of the turbulent flow. In the range of Reynolds numbers studied, the bursting frequency is best scaled on mixed variables. The conditional averaged patterns give a representation of the bursting process and show some differences between turbulent flows which develop on smooth and rough walls, in both inner and outer regions.