荆江典型河湾河势变化三维数值模型

A three dimensional mathematical modeling for the Jingjiang River

分别建立了三维水沙数学模型及考虑纵向坍塌范围的二元结构河岸崩塌力学模型,并将两者结合,建立了荆江典型河湾河势研究的三维数值模型。基于非正交网格采用局部网格可动技术处理由崩岸引起的河道摆动过程。模型采用有限体积法对方程进行离散,采用与动量插值技术相结合的SIMPLEC算法进行模型求解。对石首河湾进行了模拟研究,模拟结果表明,模型能够较好地模拟出蜿蜒河道的水沙运动规律,成功地复演了石首河湾1996年10月—1998年10月期间剧烈的河势变化(主、支汊易位及河道摆动等)过程,实测结果与模拟结果吻合较好;其中河岸坍塌是该河段河势变化剧烈的主要原因之一。

A 3-D mathematical model consisting of a 3-D flow and sediment transport module and a bank erosion module for the Jingjiang River was established. The locally-adaptive grid system based on the non-orthogonal grid is applied to simulate the lateral migration in channels due to bank erosion. The governing equations for flow and sediment transport are solved using the finite volume method （FVM） and the SIMPLEC algorithm with momentum interpolation. The 3-D mathematical model is applied to study the fluvial processes in the Jingjiang River with erodible banks. The simulated results demonstrate that this model is able to reproduce the complicated fluvial processes of the Shishou Bend during the period of October 1996—October 1998, and the computed results are well agree with the observed data.