随机波浪丁坝反射叠加形成的裂流实验

Experimental Study of Rip Currents of Intersecting Irregular Waves

摘要:

为研究随机波浪遇丁坝反射形成的裂流的特征，进行了沙坝地形丁坝反射所形成的叠加波浪生成裂流的实验。研究结果表明，沿岸一致的沙坝地形使得所形成的裂流主要受控于沿岸周期性变化叠加波浪。裂流的驱动力主要取决于节腹点之间的平均水面沿岸压力梯度，而节腹点波高差异形成的沿岸辐射应力贡献很小，驱动力的量值与范围受到波浪周期的影响。裂流的位置和宽度完全受控于波浪节点，叠加波浪场在叠加区沿岸方向上形成交替出现的环流系统和大尺度涡，此环流系统由围绕波浪节点的离岸裂流、围绕波浪腹点的向岸流和由波腹点向波节点汇聚的沿岸方向的补偿流组成。

Abstract:

To better understand the characteristics of rip current caused by crossing irregular waves，an experimental study of rip current caused by intersecting irregular waves over barred beaches was conducted. The barred beach without rip channel was adopted to eliminate the inconsistency of coastal topography caused by the rip channel，so that the rip currents was mainly controlled by the node points of waves. The driving force of the rip current is mainly the mean water surface pressure gradient pointing to the node，while the radiation stress caused by wave height contributes little due to the change of wave height along the break zone. The magnitude and range of the driving force are affected by the period. The location and width of rip currents are controlled by the wave node points. The cross-wave field forms an alternate circulation system and large-scale vortex in the alongshore direction. The circulation system includes the rip currents around the wave node points，the onshore current around the wave anti-node points，and the longshore feeder currents from the anti-node to the wave node points.