Numerical and physical modelling of breaking of fully nonlinear surface waves

Progression of nonlinear wave groups to breaking with and without wind forcing was studied numerically and experimentally. Evolution of such wave group parameters as distance to breaking and modulation depth - the height ratio of the highest and the lowest waves in the group - was described. Numerical model results demonstrated good agreement with experimental results in describing the behaviour of the distance to breaking and modulation depth as functions of initial wave steepness and wind forcing. It was shown that energy loss appears to be a function of the modulation depth at the breaking onset. Energy loss grows with modulation depth up to a certain threshold of the latter. It was also shown that breaking probability for wave groups with modulation depth below 2 is very low in the absence of wind forcing, while in the presence of wind forcing it significantly increases. Reduction of modulation depth and decreasing of severity of a single breaking even was found for certain values of wind forcing.