潮汐双向流条件下丁坝水流特性研究

以长江口南支河段为原型,概化并建立水槽数学模型,研究径潮双向流条件下丁坝附近的水流结构。研究表明:丁坝一侧河岸,丁坝下游潮差远大于上游,在丁坝上游潮差小于对岸侧,下游潮差大于对岸侧;落潮时,丁坝回流区与壅水区长度大于涨潮,转流时刻,丁坝坝头附近流速相对较大;河床底部剪切应力变化在涨落急时刻最大,且落潮大于涨潮,转流时刻坝头及坝身迎水侧剪切应力增加明显。

Study of flow structure around spur dike in bi-directional tidal flows

Aiming at the south branch of Yangtze River estuary,a numerical flume is established by channel generalization,and the research on spur dike's flow structure under bi-directional tidal flows is carried out.The results show that by the river bank of spur dike,the tidal range in the downstream of spur dike is much larger than that of upstream and the opposite bank while the tidal range in the upstream is lower than that of the opposite bank.The backflow distance and backwater areas during ebb tide are larger than that in the flood tide,and the velocity at spur dike head area is relatively larger during the turn of tidal stream.The variation of bottom shear stress reaches the peak at maximum flood or maximum ebb,and the variation during ebb tide is larger than that in flood tide,and the bottom shear stress around the spur dike head and the facing water side of spur dike body increases significantly during the turn of tidal stream.