变浅作用下的长周期重力波的实验研究

利用大型水槽设计了在由深水到近岸不同坡度处海浪在变浅作用下诱导产生的长周期重力波的实验。正态随机海浪在深水生成并沿斜坡向浅水传播,记录了不同水深处波面高度随时间的变化过程并进行统计分析和谱分析。实验数据分析结果表明,长周期重力波的能量随着水深的变浅而增高,其谱锋频率位于0.2~0.3fp附近,这里fp是深水正态海浪过程的谱峰频率。长周期重力波的能量与入射波的能量比与波面高度分布的偏度密切相关。进一步分析了两种波动的能量谱峰值比和波面高度分布偏度的相关关系,获得了经验关系,为预测近岸浅水长周期重力波提供了科学依据。

An Experimental Study on Shoaling Effect on Infragravity Waves

An experiment in a large wave flume was designed to study the infragavity waves induced by incident gravity waves on inclined beaches,the time-varying processes of wave heights at different water depths were recorded,and the statistical analysis and spectral analysis of wave heights were made.It is shown from the analysis results that the energy of infragravity wave increased with decreasing water depth,and its spectrum peak freauency was at about 0.2 to 0.3 fp,where fp is the spectrum peak frequency of incident gravity wave.The ratio of infragravity wave energy to incident gravity wave energy is strongly correlated with the skewness of wave surface elevation.It is concluded that the ratio of infragravity wave energy spectrum peak value to incident gravity wave energy spectrum peak value is correlated with the skewness of wave surface elevation,and the empirical relationship between the two is obtained,which provides scientific basis for predicting the neritic infragravity waves.