破碎波与非破碎波的特征差异

DISTRIBUTIONS OF BREAKING DETECTION INDEXES ON BREAKING WAVE AND NON-BREAKING WAVE

借助风浪实验现场的破碎事件记录,采用多种判据同时判别的方法划分破碎波与非破碎波,考查了各种破碎判据指标在破碎波与非破碎波上的分布差异。结果表明:依Hilbert变换计算的动力学判据指标和运动学判据指标在破碎波与非破碎波上的分布有明显分离,存在一个稳定的阈值区分破碎波与非破碎波;由小波方法计算的动力学判据指标在破碎波与非破碎波上的分布往往也有明显分离,但不存在一个稳定的阈值;波陡等反映波面不对称性的几何指标、瞬时波面斜率以及波高、波面极大值、波长、周期等,在破碎波非破碎波上的分布有着不同程度的交叠,无法有效区分破碎波与非破碎波。

Based on the synchronous in situ trigger signal for breaking events,using multi-breaking criterion to classify the breaking and non-breaking waves,the distribution differences of some breaking criterion indexes on breaking and non-breaking waves were examined.The results indicate that for the detection indexes in dynamic criterion and kinematic criterion were calculated via Hilbert transformation,their distributions on breakers and non-breakers were well separated,and there are stable threshold values for breaking criteria;the detection index of dynamic criterion calculated via wavelet transformation is not so good,there is no stable threshold value to distinguish breaking waves from non-breaking waves;and for geometric indexes,such as wave steepness,forward and backward steepness,horizontal and vertical crest asymmetry,and for wave height,maximum wave elevation,wave length,wave period,and even for instantaneous wave slope,there is no enough difference between their values on breaking and non-breaking waves,the breaking criteria based on such indexes are not effective.