3D Numerical Simulation of Shear Stress in Rectangular Compound Channel using Ansys Fluent Model

The precise prediction of shear stress in open channel is important in many engineering issues such as designing of sustainable channels, calculation of energy losses, and sedimentation in channels. In flood duration, due to difference in depth of flow between the main channel and the flood plains surrounding the flow, the flow velocity is also different, and subsequently the stress and distribution of stress significantly changes. In this paper, it has been shown the performance of the Ansys Fluent three-dimensional numerical model in simulating various hydraulic parameters for a rectangular compound channel with smooth and rough bed and wall. Comparison of shear stress values showed that with decreasing depth in flood plains, the amount and percentage of shear stress in flood walls, and in main channel increased and decreased respectively, and also it was shown that with increasing roughness, shear stress increased. Results also indicated that with increasing flow rate, the power flow increased and velocity and vortices were formed at the intersection of flood plains and main channels. The results of this research can play a role in designing of sustainable channels, especially at the intersection of the main channel and flood walls.