Extreme wave crest distribution by direct numerical simulations of long-crested nonlinear wave fields: Fid-Bau Portal

Extreme wave crest distribution by direct numerical simulations of long-crested nonlinear wave fields

Liu, Shuai / Zhang, Xinshu

Highlights • The unified semi-empirical single realization crest distributions for nonlinear long-crested wave fields have been developed for wave calibration before model test in wave basin. • The effects of fourth-order nonlinearity on wave crest distributions have been investigated. • Large-scale and 3-h nonlinear wave simulations with considering energy dissipation due to wave breaking have been performed.

Abstract The wave crest height qualification checks are required during the wave calibration before the model test in wave basin. However, the reliable criteria of nonlinear wave crest probability distribution in 3-h duration (full-scale) has not been well established yet. We investigate wave crest-height statistics of long-crested nonlinear wave fields using high-order spectral (HOS) method, which can take the effects of both second-order bound waves and third-order free waves into account. The energy dissipation effects due to wave breaking were included by employing an eddy viscosity model. Sensitivity analyses to the wave breaking onset criterion have been performed. Validation is provided by comparing the obtained numerical results with the available calibration test data. Based on extensive and direct numerical simulations, semi-empirical single realization distributions for wave calibration have been developed through 3-parameter Weibull fitting and systematic regression analyses. Particular attention has been paid to the tail of upper bound of wave crest distributions. The effects of wave steepness and water depth on the maximum wave crest height in 3-h duration have been examined. It is found that with the increase of wave steepness, the extreme wave crest height increases until it reaches a critical value. In addition, for the scale water depth k p h < 1.36, the maximum crest height decreases as the water depth increases, while in the opposite case the maximum crest height increases as the water depth increases. Moreover, it is confirmed that that the fourth-order nonlinearity does not have significant effects on the distribution of the wave crest height.