Apparent Shear in an Asymmetric Compound Channel

Abstract

For uniform flow conditions in a compound open channel, much of the hydraulic resistance may be ascribed to channel roughness and flow characteristics with further accounting for other forces. The resistance to flow along the boundary of the compound channel is exhibited in the form of shear stress along the periphery, known as boundary shear. Distribution of this boundary shear across the lateral direction of the compound channel is one of the challenging tasks. An expression to predict this boundary shear distribution is presented depending on geometric and hydraulic parameters. The performance of the model is found to give better re-sults as compared to models of other investigators when applied to experimental data and FCF data. Three phenomenological generalized expressions are also presented and applied to asymmetric compound channels of various geometric and hydraulic parameters for delivering the apparent shear at any possible interface. The consequence of the approach for predicting the apparent shear is analyzed through an experimental investiga-tion concerning the boundary shear distribution in asymmetrical compound channels of different width ratio and flow conditions. Moreover, the current approaches are also capable of evaluating the intensity of momen-tum transfer across different interfaces and locating the zero shear interfaces for prediction of discharge by ar-ea method of reasonable accuracy.