A BOUSSINESQ MODEL FOR WAVES BREAKING IN SHALLOW-WATER

A simple description of wave breaking in shallow water is incorporated in the Boussinesq equations by using the concept of surface rollers. The roller is considered as a volume of water being carried by the wave with the wave celerity. The effect vf the roller is included in the vertical distribution of the horizontal velocity, which leads tn an additional convective momentum term. The breaking criterion is related to the local slope of water surface and the thickness of the roller is determined from simple geometrical considerations. Although the model is simple, it is capable of representing a variety of processes such as the initiation and cessation of wave breaking, the evolution of wave profiles before,, during and after wave breaking, the initial conversion of potential energy into forward momentum flux, and the associated horizontal shift between the break point and the point where the setup in mean water level is initiated. Results are presented for regular and irregular wave trains and comparison with measurements shows good agreement.