粗糙珊瑚岸礁礁面附近波浪增水实验研究

Experimental Study on the Wave-induced Setup Around Rough Fringing Reef

通过在波浪水槽中采用概化的珊瑚岸礁物理模型来研究珊瑚礁海岸附近波浪增水的变化规律,包括平均自由表面的沿礁变化以及礁坪上的最大增水值。物理模型实验分别测试了不同礁面糙率密度影响下的一系列不规则波工况。结果分析表明:礁面粗糙时礁坪上的透射波高和最大增水值均相对于礁面光滑时减小;通过两个无量纲参数分析表明光滑礁面时,礁坪上最大增水随波要素的变化规律与此前研究数据基本吻合,前人研究推荐的无量纲数ηr/T gHS0 和(ηr+hr)/HS0 需考虑礁面粗糙度的影响;礁面粗糙程度不同时,礁坪上的透射波高随礁面糙率密度的增大而减小,礁坪上的最大波浪增水则随之增大;最后通过沿水深积分对波浪求平均的水平一维动量方程解释了本实验的观测现象。

Wave-induced setup around reef coast was investigated based on an idealized physical reef model in a wave flume. Special attention was paid to both the variation of mean water level across the reef and the maximum wave setup on the reef flat. A series of irregular waves were tested on the rough reef surfaces with different roughness densities. Results showed that, both the transmitted wave height and the maximum wave setup on reef flat reduced when the reef surface was rough. Dimensionless analysis showed that the maximum wave setup on smooth surface varied with incident wave condition similarly to those demonstrated in previous studies, and the dimensionless parameters η r /T gH S 0 and (η r +h r )/H S 0 proposed in literatures could be further improved when the surface roughness was taken into account. For different surface roughness, the transmitted wave height on reef flat decreased with increasing surface roughness density, but the maximum wave setup increased as roughness density increase. Finally, the depth-integrated wave-averaged one-dimensional horizontal momentum equation was used to interpret the laboratory observations in this study.