弗劳德数影响下的沙质河床丁坝群局部冲刷数值模拟

Numerical Simulation of Local Erosion of Spur Dike Groups in Sandy Riverbed Under Influence of Froude Number

为分析弗劳德数对沙质河床丁坝群局部冲刷的影响,基于MIKE21对三种泥沙粒径沙质河床在不同弗劳德数下的丁坝群局部冲刷进行数值模拟,总结了冲刷范围及特征断面的变化规律。结果表明,局部冲刷除Ⅱ号坝头产生淤积外其余丁坝坝头均产生局部冲刷;同一弗劳德数下,泥沙粒径越小,冲刷范围及断面变化越大,高弗劳德数时更为明显,而同一粒径下,弗劳德数越大,冲刷范围及断面变化会越大,在泥沙粒径较小时更为明显;在泥沙粒径较小、弗劳德数较大时,冲刷范围几乎影响整个丁坝群河道且首坝附近河床整体为先冲后淤。

In order to analyze the influence of Froude number on local erosion of spur dike groups in sandy riverbed,numerical simulation of local erosion of spur dike groups in sandy riverbed with different Froude numbers was carried out based on MIKE21,and the change rules of erosion range and characteristic section were summarized.The results show that the local erosion occurs in all the other spur dike heads except NoⅡdam head.Under the same Froude number,the smaller the sediment particle size is,the greater the erosion range and cross section changes are,and the higher the Froude number is more obvious;Under the same particle size,the greater the erosion range and cross section changes,and the smaller the sediment particle size is,it is more obvious;When the sediment particle size is small and the Froude number is large,the erosion range affects almost the whole channel of the spur dike groups,and the whole riverbed near the first dam is washed first and silted later.