Depth-averaged shear stress and velocity in open-channel flows

Turbulent momentum and velocity always have the greatest gradient along wall-normal direction in straight channel flows; this has led to the hypothesis that surplus energy within any control volume in a three-dimensional flow will be transferred toward its nearest boundary to dissipate. Starting from this, the boundary shear stress, the Reynolds shear stress, and the velocity profiles along normal lines of smooth boundary may be determined. This paper is a continuous effort to investigate depth-average shear stress and velocity in rough channels. Equations of the depth-averaged shear stress in typical open channels have been derived based on a theoretical relation between the depth-averaged shear stress and boundary shear stress. Equation of depth mean velocity in a rough channel is also obtained and the effects of water surface (or dip phenomenon) and roughness are included. Experimental data available in the literature have been used for verification that shows that the model reasonably agrees with the measured data. DOI: 10.1061/(ASCE)HY.1943-7900.0000271 CE Database subject headings: Boundary shear; Reynolds stress; Velocity distribution; Open channel flow; Turbulent diffusion; Shear stress. Author keywords: Boundary shear; Reynolds stress; Velocity distribution; Open-channel flow; Turbulent diffusion.