4. Experimental and Numerical Analyses of Boundary Shear Stress in Non-prismatic Compound Channel

As boundary shear stress is an important parameter in open channel flow so experiments are carried out in non-prismatic compound channel. These experimental channels comprising of rectangular main channel, two symmetrically disposed diverging flood plains. The boundary shear stress distribution cannot be determined easily as they depend upon the velocity field, the shape of the cross section, and the boundary roughness. Variation of shear on flood plain and main channel with respect to the relative flow depth and divergence angle has been demonstrated. The present experimental non-prismatic compound channel is having diverging flood plain. Here, experimentations were done with two water depth ratio (Dr) such as 0.4 and 0.5 and two diverging angle such as 5.93 and 9.83°. As a complementary study of the experimental research undertaken in this work, one numerical hydrodynamic tools, viz., three-dimensional CFD model (ANSYS—FLUENT) is applied to simulate the flow in non-prismatic compound channel. This study aims to validate ANSYS—FLUENT simulations of open channel flow by comparing the data observed in the hydraulics laboratory of the National Institute of Technology, Rourkela. In this study, I have used four turbulence models to validate the result up to the at most accuracy. The four models are as follows: LES, k-ɛ, k-ω, and SST. The experimental results were taken as the reference, and all the models simulation result of boundary shear stress is compared with it, among the four models LES was given the approximate result and was taken as the best model for the analysis of boundary shear stress for non-prismatic compound channel.