Five kinds of energy dissipation formulations due to wave breaking are incorporated into a spectral wave model through parameterizations by two methods. The spectral wave model is based on the wave action balance equation with diffraction effects. The laboratory data from an experimental study of random waves shoaling and breaking on steady ebb currents at an idealized inlet are used to evaluate the performance of spectral wave breaking formulations in the wave and current coexisting field. Model to data comparisons show the bore-based formulation of Battjes and Janssen with a breaker height of 0.73 times the water depth produces the best fit in the applications studied herein.
In most coastal inlets and estuaries, where a great deal of human activity takes place, strong tidal currents may have a dramatic effect on wave transformation. Waves shortened and steepened by ebb currents lead to considerable breaking in both areas outside and inside the navigation channels. With strong currents, wave blocking becomes a serious navigation hazard. Therefore, reliable numerical predictions of waves are crucial in coastal engineering studies such as shore protection, harbor construction, nearshore morphological evolution, navigation channel maintenance and maritime disaster reduction. One of the most important factors in the reliable modeling of nearshore waves is the characterization of wave breaking, since turbulent dissipation of the wave energy becomes the dominant dissipative mechanism and breaking processes play a quite important role in the wave transformation once waves are broken. In the absence of ambient currents, Zhao et al. (2001) examined five types of parameterizations for wave breaking in a two-dimensional elliptic wave model. They found that the formulations of Battjes and Janssen (1978) and Dally et al. (1985) performed better consistently and were robust to be used in their mild-slope wave equation model.
