Depth-Averaged Velocity and Boundary Shear Stress Prediction in Asymmetric Compound Channels

Abstract

When a river overflows, either side of its flood plain during flood is named as asymmetric compound channel; however, if two adjacent flood plains are inundated, it is called as symmetric compound channel. Due to the complex flow mechanism at the junction between main channel and flood plain, modeling of depth-averaged velocity and boundary shear stress in an asymmetric compound channels becomes an exigent task. The analytical solution of the Shiono and Knight Method accounts three governing parameters, i.e., lateral shear, bed friction and secondary flows for prediction of these flow variables. In order to investigate the influence of these governing coefficients on flow parameters, experiments were employed in asymmetric compound channels. Variation of boundary shear stress and depth-averaged velocity across the channel was investigated. Some experimental data sets from large flood channel facility and from measurements taken by other researchers have also been used in this study. The variation of three calibrating coefficients, i.e., eddy viscosity coefficient (\(\lambda \)), friction factor (f) and secondary flow coefficient (k) against the geometric and hydraulic parameters, has been studied. Expressions for secondary flow coefficients in terms of hydraulic and flow parameters have been procured for different panels which are required to get the distribution of boundary shear and depth-averaged velocity. The performance of the models has been successfully proved for experimental channels and natural river data sets.