Wave Period Distribution in Mixed Sea-States

Abstract

The statistical distribution of zero up-crossing wave periods in Gaussian mixed sea-states is examined by using numerically simulated data. Nine different kinds of bimodal spectra are used to analyze the effects of the relative energy ratio and the peak frequency separation between the low- and high-frequency wave fields on the wave period distribution. Observed results are compared with predictions given by probabilistic models suitable for practical applications. Numerical results reveal a different behavior for low- and high-period bands. Furthermore, comparisons of the empirical data with some probabilistic models often used in practice shows that none of these models is able to characterize adequately all the cases of combined sea-states examined. In fact, they might be used only in the case of wind-sea dominated sea-states with small separation between spectral frequency peaks. However, a model recently proposed by Myrhaug and Slaattelid [1] represents adequately the observed distributions of wave period.