Numerical investigation of wave amplitude spectra effects on focusing wave generation

Focusing waves are often considered as an effective simulation of freak waves observed in oceans, or extreme sea states for marine structures design. The understanding of factors in generating prescribed focusing wave is of great importance for its generation in both numerical and physical wave tank. Based on the fully nonlinear potential theory solved by the QALE-FEM, this paper numerically investigates the effect of wave amplitude distribution over the frequency band under a series of the crest elevation parameters and frequency ranges on focusing wave generation, including focusing wave crest elevations and focusing positions. The results suggest that focusing wave crest elevation is significantly affected by the wave amplitude distribution especially for target waves with large wave crests or those are assigned at low frequency domain. Moreover, generation positions of focusing wave are also strongly correlated to amplitude spectra through phase shift of the wave surface and wave nonlinearity denoted by wave steepness.