Experimental study on multi-directional wave focusing and breaking in shallow water

The breaking waves are generated in shallow water wave basin by decreasing the wave maker frequencies linearly and then the generated component waves being focused at one specified point in this paper. Two different component distributions of constant wave amplitude (CWA) and constant wave steepness (CWS) are used. The focusing and breaking wave characteristics, the transformation of the focusing wave packet, the spectral variation during the wave packet propagation, the water wave surface properties and the effects of wave directionality on the focusing wave characteristics were experimentally studied. The results show that the maximum surface elevation generated by higher depth or CWS spectrum is higher than that by lower depth or CWA spectrum and is dependent on the wave directionality. The wave spectra are distinctly changing during the packet propagation, and the energy loss and the shift of higher frequencies can be distinctly observed from the analyzed frequency spectra before and after the wave breaking.