Numerical analysis of flow characteristics for idealised Y-shaped channels

Abstract

Channel confluence and bifurcation flows are common phenomena in a natural river. Understanding the characteristics of these dividing flows can help engineers to make decisions on flood risk reductions. In this study, a numerical model has been applied for idealised Y-shaped channels in both cross-sections of rectangular and trapezoidal. InfoWorks ICM software is used to run the numerical analysis on the proposed model. The model included the main channel upstream with a bifurcated angle of 45° at each downstream channel. A series of simulations have been carried out to investigate the effects of various flow characteristics on the water depths and flow velocities. These characteristics are manning’s roughness coefficient, the width of the channel, and the shape of the channel cross-section. Results show that the increase in manning’s roughness coefficients caused a decrease in flow velocities and increased the water depths for both rectangular and trapezoidal cross-sections. Furthermore, increases in channel widths have caused decreases in flow velocities and water depths for both rectangular and trapezoidal cross-sections. In addition, the rectangular cross-section showed lower flow velocities and water depths compared to the trapezoidal cross-section. The findings from this study may provide a good understanding of the flow characteristics in a bifurcation river to mitigate floods.