Turbulent flow in a plane channel having one or two rough walls

Abstract

The assumption of universal velocity profiles over smooth and rough surfaces is widely used in calculations on flow in rough channels. Experiments on fully developed turbulent flow in a rectangular channel with variable aspect ratio were performed to determine the parameters of the velocity profiles over two-dimensional rectangular roughnesses. The pressure and velocity profiles in the fully rough flow regime were measured in channels with one and with two rough walls. The results show that the slopes of the nondimensional velocity profiles in the smooth and rough zones decrease with the increasing relative roughness, height and drag of the rough wall, contrary to the generally accepted assumption of a constant profile slope. The profile parameters were correlated as functions of the channel- and roughness geometry and were used in a transformation method which was applied to data from experiments on rectangular and annular channels carried out by other investigators.