Analytical Study of Flow Field in Non-Prismatic Compound Channel with Converging Floodplains Using Modified SKM

Prediction of flow filed in compound channel is an important task for hydraulic researches because of three-dimensional nature of flow. The complexity of the problem increases, significantly, when floodplains geometry changes from prismatic to non-prismatic form. In non-prismatic compound channels with converging floodplains, the main feature consists of the mass and consequent momentum exchange between the floodplains and the main channel. In the present work based on the depth-averaged Navier-Stokes equation an analytical method is proposed and used to predict the depth-averaged velocity and boundary shear stress distribution in non-prismatic compound channels with converging floodplains.  In order to consider the effect of the secondary flows in the depth-averaged Navier-Stokes equation, temporal mean velocity components are assumed to be a portion of the depth-averaged velocity. Also, since the flow condition is not uniform; the flume bed slope has been replaced by the energy line slope. The results of the proposed analytical method are then compared with the experimental data, the modified SKM suggested by Rezaei and Knight (MSKM) and the SKM method. The study shows that there are good agreement between the results of the new analytical method and the experimental data.