Boundary shear stress in open channel flow: A comparison among six methods

Abstract

Six methods for the computation of the boundary shear stress distribution, and the mean bed and wall shear stresses in prismatic open channel flows are compared against laboratory data. The comparisons indicate that the widely used Vertical Depth Method (VDM) does not provide reliable results. The Guo and Julien Method (GJM) with empirical correction factors gives the best prediction of the mean wall and bed shear stresses in smooth rectangular channels. The Ramana Prasad and Russell Manson Method (PMM) and Knight et al. Method (KAM) are suitable predictors of the mean bed and wall shear stresses in rough rectangular channel and in circular channel with a flat bed, respectively. The Merged Perpendicular Method (MPM) and theYang and Lim Method (YLM) provide the best predictions of the local shear stress for trapezoidal and circular channels. Finally, the study highlights the deficiencies in the MPM andYLM to predict reasonably the boundary shear stress distribution in compound channel