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中文摘要：
弯曲河段中因二次流运动引起的横向输沙是引起崩岸的重要因素之一．为研究急弯河段中二次流运动对水沙输移的影响，以下荆江石首急弯河段为例，运用能考虑二次流影响的Delft3D模型对其进行计算，并用实测水沙资料验证模型的可靠性．在此基础上，详细分析了二次流运动对流速及含沙量分布的影响，同时分析了不同位置处二次流附加应力项、水面比降项及阻力项的相对大小关系．计算结果表明：考虑二次流后，能更有效地模拟弯道处的环流水力特性及横向输沙特性；二次流对水沙输移的影响效果在急弯河段十分突出，只有当来流流量足够小时，才能忽略二次流的影响．
英文摘要：
In a sharply curved channel, the transverse transport of sediment caused by secondary flows is one of the important factors that can lead to bank collapse. In order to investigate quantitatively the effect of secondary flows on the transport of flow and sediment in a sharply curved channel, the Shishou river bend in the Lower Jingjiang Reach is taken for example. The Delft3D software, which can account for the effect of secondary flow, is used to simulate the distributions of flow and sediment factors~ and the model＇ s capacity was validated using the measured water levels, flow velocities and sediment concentrations. The effects of secondary flows on the transverse distributions of flow and sediment factors, velocity field and sediment concentration distribution in the whole study reach are then investigated in detail. In addition, the relationship between the specified terms in the flow governing equations is obtained at the five observa tion points, covering the additional stress for secondary flow, water surface slope, and bed roughness. The results show that the characteristics＇of circulating hydraulic and sediment transverse concentration can be predicted more accurately considering the effect of secondary flows. The effect of secondary flows is sig- nificant in the process of flow and sediment transport in a sharply curved channel~ and it can be neglected only if the incoming discharge is relatively small.
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