Breaking waves in the surf-zone

This work deals with breaking waves inside the surf-zone. A 1-D breaking wave model is developed which describes the time variation of surface profiles and velocity field in the surf-zone. The present model is constructed on the framework of the traditional equations and can be applied in the entire coastal region. So the problem that the standard Boussinesq equations fail in the surf-zone has been remedied.;The model differs from previous Boussinesq type models for breaking waves which either used an artificial dissipation term to account for the energy dissipation or specified an expression for the effect which the breaking has on the momentum equation by using empirical and ad-hoc ideas about the velocity profiles. The roller concept adopted in the present model only serves as a source of vorticity and turbulence. The vorticity model generates a smooth and continuous velocity profile and the velocity is close to the wave celerity at the upper front part of the breaking waves.;The present breaking wave model contains breaking terms derived directly from the Reynolds equations. Breaking terms are introduced to the momentum equation to account for the effect of the rotational part of velocity in the non-linear and the frequency dispersive terms, and the effect of turbulent stresses. These breaking terms, together with remaining terms in the momentum equation, approximately simulate the momentum balance in the surf-zone.;Numerical results are compared against the results from the traditional Boussinesq model and the experimental data. The comparison with experimental data shows good agreement on wave height and setup distributions, undertow profiles, and wave kinematics.;Regarding the vorticity and the turbulence as the two most important features of breaking waves in the near shore region, the present study addresses these features by avoiding use of the potential flow assumption. It is accomplished by splitting the velocity into a rotational and an irrotational part. The rotational part is assumed to be of the same order of magnitude as its potential counterpart. Using traditional Boussinesq approximations, the rotational part of the velocity is determined by a simplified vorticity transport equation which essentially specifies the vertical spreading of the vorticity.