潮汐流影响下珊瑚岛礁附近波浪传播变形和增水试验

Laboratory study of wave transformation and wave-induced setup over reef islands under the effect of tidal current

为揭示潮汐流影响下珊瑚岛礁附近波浪的运动特征,通过波流水槽试验对潮汐流存在下规则波的传播变形和增水规律进行了研究,测试了一系列的潮汐流流量并对比正向流、反向流以及无流的情况。研究结果表明:反向流使波浪破碎点向远海侧移动,正向流则使其向海岸侧移动,反向流存在时破碎带内的湍流较正向流时更为剧烈;反向流时破碎点附近入射波能量由主频波向高次谐波发生转移更为显著;潮汐流的存在对波浪反射、透射和能量耗散并无明显影响;正向流造成礁坪上波浪增水减少,反向流则促进增水的增长,增水最大值与潮汐流流量间存在显著的线性关系。研究成果可望为岛礁工程的建设和维护提供一定的理论参考。

To study the characteristics of wave motions over reef islands under the effect of tidal current,laboratory experiments were performed in a wave-current flume to investigate the wave transformation and wave-induced setup in the presence of tidal current. A series of tidal flowrates were tested,and three flow regimes（ shoreward,seaward and no-flow） were compared. Results show that the seaward flow moves the breaking point to the offshore side while the shoreward flow moves it to the coastal side. The turbulence in the surf zone associated with the seaward flow is stronger than that with the shoreward flow. Incident wave energy around the breaking point transferred from primary waves to their higher harmonics,and this type of transfer is more evident with the seaward flow. The tidal current has insignificant effect on wave reflection,transmission and energy dissipation. The shoreward flow decreased the wave-induced setup on the reef flat while the seaward flow increased it,and there is strong linear relationship between the maximum wave setup and the tidal flowrate. This study may provide theoretical guidance for construction and maintenance projects around those reef islands.