Relation between occurrence probability of freak waves and kurtosis/skewness in unidirectional wave trains under single-peak spectra
Résumé
An accurate prediction about the occurrence probability of freak waves in unidirectional wave trains is crucial for avoiding disasters and losses in marine operations. Based on a two-dimensional High Order Spectral numerical wave tank, here the quantitative relation between the occurrence probability of freak waves and kurtosis/skewness considering the influence of Benjamin-Feir Index and relative water depth is investigated. A wide range of 25 single-peak spectral waves is simulated for data collection and further statistical analysis. Results show that the correlation between the occurrence probability of freak waves and skewness depends on the Benjamin-Feir Index and no uniform linear relation is deduced. In contrast, the occurrence probability of freak waves has a strong correlation with kurtosis, irrespective of Benjamin-Feir Index, relative water depth, and peak enhancement factor. An empirical formula for the occurrence probability of freak waves is obtained: P freak (%)=0.29kurtosis-0.8, a little deviation from the one based on the Modified Edgeworth-Rayleigh (MER) weakly nonlinear model.
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