Depth-induced wave breaking in a non-hydrostatic, near-shore wave model

The energy dissipation in the surf-zone due to wave breaking is inherently accounted for in shock-capturing non-hydrostatic wave models, but this requires high vertical resolutions. To allow coarse vertical resolutions a hydrostatic front approximation is suggested. It assumes a hydrostatic pressure distribution at the front of a breaking wave which ensures that the wave front develops a vertical face. Based on the analogy between a hydraulic jump and a turbulent bore, energy dissipation is accounted for by ensuring conservation of mass and momentum. Results are compared with observations of random, uni-directional waves in wave flumes, and to observations of short-crested waves in a wave basin. These demonstrate that the resulting model can resolve the relevant near-shore wave processes in a short-crested wave-field, including wave breaking and wave-driven horizontal circulations. ► Non-hydrostatic models require high vertical resolutions in the surf zone. ► To ameliorate this the hydrostatic front approximation is suggested. ► This permits low vertical resolutions in the entire domain, including the surf zone. ► Wave processes in a short-crested wave-field are adequately resolved.