Experimental study on dynamic pressure under the crest of unidirectional nonlinear waves

The dynamic pressure under wave crests is experimentally studied in three different scenarios, and the influence of nonlinearity as well as the dispersive effect is revealed by comparing with the corresponding linear theoretical predictions. For regular waves, the nonlinear effect plays different roles in modifying the upper and lower sections of the dynamic pressure under the wave crests with the boundary determined by the strength of nonlinearity. Regarding irregular waves, the dynamic pressure under wave crests is mainly affected by the surrounding individual waves within the same wave group, and in most cases its variation is dominated by the dispersive effect, exhibiting a greater magnitude than its counterpart in regular waves. As to focused waves, the same large crests can be realized in the time domain with different methods, but the discrepancy of dynamic pressure is very noticeable due to the fundamentally different nonlinearities involved in the focusing process. Therefore, to accurately evaluate the dynamic pressure under wave crests in the ocean, the dominant nonlinearity at the current evolutionary stage, as well as the dispersive effect, must be considered.