游荡型河流的平面二维水沙数学模型

为使数学模型能模拟游荡性河流因水流弯曲、分汊等导致的环流输沙作用，本文首先在悬移质泥沙对流扩散方程中增加了横向输沙项，然后引入适合游荡型河流的塌岸模式及局部动网格技术和网格融合技术，解决了河岸变形模拟和河道整治工程导致网格再生、床沙级配变化模拟等关键性难题，开发出可模拟游荡性河流河床演变且可反映河道整治工程作用的平面二维水沙数学模型。最后，以黄河下游柳园口—夹河滩河段为例，应用本文模型对游荡型河流河势变化进行了数值模拟，结果表明本模型能够真实地模拟出游荡型河流独特的河床演变过程。

Two_dimensional numerical model of flow and sediment transport for wandering rivers

The two_dimensional numerical model of flow and sediment transport for wandering rivers is presented. In the model an additional term accounting the lateral sediment movement due to the circulation flows is included. A new approach for simulating the collapse of river bank composed of cohesive materials is proposed. The local moving grid and mesh mergence techniques are also developed to trace the bank migration. The techniques make the model possessing well mass conservation and computational stability, so that it is suitable for the simulation of long term fluvial processes. The proposed model is applied to study the evolution of a typical reach of wandering river in the Lower Yellow River. The simulation results well agree with the field observation data.