长江中游分汊型河道二维水沙数值模拟

2D flow and sediment mathematical model for braided channel of the Yangtze River

针对长江分汊型河道边界复杂的特点,建立了基于多连通域贴体正交曲线坐标系下的二维水沙数学模型.模型采用有限差分法离散平面二维水流运动方程和泥沙输运方程,通过非恒定流多个时间步逼近模拟恒定流的方法,模拟了多分汊河段的水位、流速场及泥沙场.将所建模型初步应用于长江中游典型分汊河段——窑监河段的水沙过程模拟,结果表明模型能较好地模拟分汊河道的水沙运动规律.

Depending on the complex boundaries of braided channel in the Yangtze River,a 2D flow and sediment mathematical model is developed based on multiply connected domain body-curve orthogonal grid system.The 2D water movement equation and sediment transport equations are dispersed by the finite difference method under the body-curve orthogonal grid system.The water level,velocity field and sediment field of braided river are simulated by the model through approaching steady flow by multi-time step simulation of unsteady flow.The model is applied to simulate the water and sediment movement of typical braided reach in the Yangtze River.The results of the verification indicate that the model could well simulate the movement of water and sediment in braided channel.