Comparison of Two Different Secondary Flow Correction Models for Depth-averaged Flow Simulation of Meandering Channels

Several secondary flow correction models have been proposed in the literature to account for the 3d flow characteristics of secondary flow which is often lost in depth-averaged hydrodynamic model. In this paper two typical correction models are selected as representatives which are Lien (L) and Bernard (B) models. And one singular bend channel and one meandering channel are applied to evaluate their performances in flow simulation. The simulation results in water surface level and longitudinal velocity distributions across sections of L and B model are compared with that of traditional depth-averaged model with no correction (N model). The results show that the water surface level of B model is a bit higher than that of the other models in the two flumes. As for velocity simulation results, B model performs best by comparison with the other two models, especially when the channel bends become complex. B and L model mainly improves the velocity simulation results around the wall region. The velocity distributions of L model become irrational in flow simulation of the complex meandering channel. While B model works well in sharply curved channel and complex meandering channel. Therefore, B model is applicable for flow simulation in meandering channels. The analysis of the distribution of correction terms of B model demonstrate that the correction term is at the same order of the viscosity stress term and the maximum values of it are around the wall region which enabled the redistribution of the longitudinal velocities.