Three-dimensional numerical simulation of water flow characteristics in wide and narrow rivers

In the mountainous area, due to the influence of the topography and the incoming water, it is easy to form a wide and narrow river channel. The water flow structure is different from the single river channel, and the change trend is related to the river channel section shape and flow. The three-dimensional numerical model is established by simulating the wide and narrow rivers in the mountainous area of Sichuan. The results show that the average cross-sectional velocity of the narrow section is positively correlated with the flow rate, but the variation is not obvious in the wide section; the shear stress of the bed surface is basically symmetrically distributed along the cross-sectional direction; the shear stress of the side wall of the narrow section is negatively correlated with the height of the side wall, and the maximum value appears on the water surface, due to the influence of the recirculation zone, the shear stress of the side wall increases firstly and then decreases with the shear height of the side wall; the shear stress of the side wall has a scouring effect on the river bank, which makes the narrow section of the river bed having a tendency to continuously cut down, and the wide section of the river bed is continuously widened.