Spatial and temporal evolution of nonlinear wave groups

The evolution of unidirectional nonlinear wave groups with narrow spectrum along the tank is studied using digital processing of video-recorded sequences of images of contact line movement at the tank side wall. The experimentally obtained data are compared with the solutions of the Dysthe equation written both in the temporal and in the spatial forms. Both versions of the Dysthe equation are solved numerically and the results are compared quantitatively with the experiments. Both wave frequency and wave number spectra are presented. It is demonstrated that accounting for the 2nd order bound (locked) waves is essential for getting good agreement between the measured and the computed wave spectra.