THE NONLINEAR EXCITATION OF SYNCHRONOUS EDGE WAVES BY A MONOCHROMATICWAVE NORMALLY APPROACHING A PLANE BEACH

The possible excitation of synchronous edge waves by a monocromatic wa ve normally approaching a plane beach is studied. Use is made of the f ull three-dimensional water wave theory but only beach angles beta = p i/(2N), where N is an integer, are considered, A weakly nonlinear stab ility analysis is used to investigate the interaction of subharmonic, synchronous and 3/2-frequency edge waves with the incoming wave field. It is shown that values of beta exist for which an energy transfer fr om the incoming wave to the synchronous edge waves takes place through the intermediary of the subharmonic components.