Influence of additional resistances on numerical simulation of 2 D flow at river channel confluences

Due to separated flow and free shear flow, the turbulent properties at river channel confluences are much different from that in common channels. By comparing experimental data with numerical simulations, the significance of additional resistances resulting from separated flow and free shear flow is illustrated in this study. Because of the two-dimensional (2D) assumption, the vertical velocity variation is not considered in 2D models, which can result in large errors for high flow rate ratios. In contrast, the assumption is generally valid for low flow rate ratios. Thus, the proper treatment of additional resistances in numerical simulation of confluence flow is vital to the success of solving engineering problems.