基于动网格技术对泥沙输运和局部冲淤的数值模拟

Numerical simulation for sediment transport and local scour and deposition with dynamic mesh

该文建立泥沙输运和床面冲淤的垂向二维模型,采用SST k-ω模型模拟湍流并使用VOF法处理自由面运动,同时用动网格技术实现水底地形变化,计算了水平射流的泥沙冲淤问题。流场和地形变化的计算结果与实验数据基本一致,从而验证了计算模型的可靠性。在此基础上,该文进一步研究动床条件下的带横向沟槽明渠流动中水底地形随时间的变化过程。结果表明,水流在上坡过程中,由于水深减小流速增大,上坡部分受到局部冲刷作用;而坡顶处由于泥沙沉积形成一个小沙丘,坡顶位置在来流作用下逐渐向下游推移,最终地形趋于平衡状态。

This study build a vertical 2-D sediment transport model to simulate the bed scour process due to horizontal jets, where the turbulent flow is simulated by SST k-ω model, the free surface is captured by the VOF method and the bed deformation is realized using dynamic mesh. In the simulation of horizontal jet scour in an open channel flow with a lateral trench, the flow field and bed shape agree well with experimental data, which demonstrates the reliability of this computational model. In addition, in the movable bed condition, open channel flow with a lateral trench is simulated and the deformation of bed shape over time is discussed. It is found that there is local scour caused by accelerated flow on the upslope and a small dune formed by sediment deposition at the top of the slope. The top of the slope is gradually moving downstream and finally the terrain tends to be balanced.