Numerical Simulation of 3D Flow Pattern at Open-Channel Junctions

This paper numerically investigates the 3D flow pattern at the 900 equal-width rectangular open channel junction. The Reynolds-Stress Model (RSM) is applied to simulate the turbulent flow. The flow is analyzed under steady-state conditions. Shumate's experimental findings are used to test the validity of the numerical modeling. Comparison of the modeling data with the experimental ones indicated a close proximity between the flow patterns of two sets. The average prediction error of velocity showed a range between 3.5%-10%. Effects of the discharge ratio on separation zone dimensions, created in the main-channel, downstream of the junction, indicated an inverse relation, where increase in discharge ratio, will entail a decrease in the length and width of the separation zone. In this research, the shape index of separation zone was found to be an average value of 0.18. Comparison of the results further showed that the increment in discharge ratio will lead to decreased in the maximum value of bed shear stress. The study also found the Fluent as a powerful numerical tool for the analysis of flow pattern in the feasibility stage of the hydraulic engineering projects.