河型发育过程的二维数值模拟研究

改进已有二维平面水沙模型,进一步考虑河床粗化、弯道二次流及河床结构对泥沙输运的影响;并针对河湾形态对崩岸的影响提出新的非粘性土崩岸模拟方法,使其能模拟边滩的形成。利用改进后模型分别对Yen弯道水槽泥沙冲淤试验及Friendkin室内弯曲小河塑造试验进行模拟;模拟结果与试验观测资料吻合较好,表明考虑弯道对泥沙输运及河岸崩塌影响的模型能够更准确反映天然河流演化过程,为研究河型演化机理及各控制因素变化规律提供新手段。

2D Numerical simulation for the formation of channel pattern

A sediment transport and bed morphology model considering the secondary flow and non-uniform of sediment with armored beds was established based on the 2D depth-averaged hydrodynamic model previously developed in this paper.A simple simulation method considering the influence of river bend was adopted in the non-cohesive bank erosion,so that it is capable to simulate the evolution of sand bars.A 180°bend with a constant radius under unsteady flow conditions and the laboratory experiments of Friedkin on the initiation and evolution processes of non-cohesive meandering channels was simulated with the model,the results agree well with field measurements,it demonstrates the extended model can reflect the formation mechanism of river bend.The extended model can be applied to simulate fluvial processes to study the transformation mechanism of alluvial rivers.