短峰畸形波生成、演化过程的外部特征研究

在实际海况中，由于波浪组分方向不同，使海浪常表现为三维短峰波，与二维长峰波相比，有诸多异同特征。为了研究三维畸形波生成和演化过程中异常大波的外部特征以及大波间的关联，本文采用色散和方向聚焦方法在物理水池中模拟了短峰畸形波的整个生成和演化过程。研究结果表明，生成和演化过程中出现的异常大波沿着方向分布函数峰值方向演化，具有一定程度“对称”特征；根据异常大波的特征参数可将该过程分成3～4个典型的阶段，这意味着可以根据异常大波的特征参数判断其所处阶段及预测其演化趋势；三维畸形波生成和演化过程可能会跳过“波群”或者“深谷”阶段，与二维畸形波相比，时−空范围较小，这意味着在三维波浪场中，与畸形波相关的深谷和波群的发生概率较低。

Study on the external characteristics of the generation and evolution of short-crested freak waves

In the real sea state, the differences in directions of component waves result in three-dimensional short-crested waves, which have many different characteristics compared to two-dimensional long-crested waves. Therefore, in present study, the whole generation and evolution processes of short-crested freak waves are experimentally simulated by dispersive and directional focusing of component waves, in order to examine the external features and relationship of the abnormal large waves occurring during the processes. The results indicate that the abnormal large wave evolves symmetrically along the peak wave direction and undergoes a three- or four-stage process, each stage is indicated by the characteristic parameters of the abnormal large wave, it implies that the characteristic parameters can be used to identify the stage which the large abnormal wave is in and predict the variation tendency; and that compared to the two-dimensional cases, the “wave group” and “deep trough” stages are likely to be skipped, as a result, the spatio-temporal spans of the generation and evolution processes are smaller for the three-dimensional cases, it implies that in three-dimensional wave fields, the deep troughs and successive large waves (wave group) associated with freak waves may have a low probability of occurrence.