DIFFRACTION IN SWAN

To accommodate diffraction in conventional spectral wave models, a phase-decoupled refraction-diffraction approximation is suggested. It is based on the mild-slope equation for refraction-diffraction, ignoring phase information. It does therefore not permit applications in harbours. The third-generation wave model SWAN (Simulating WAves Nearshore) was used for the numerical implementation based on a straightforward finite-difference scheme. Computational results is extreme diffraction-prone situations agree reasonably well with analytical solutions, observations, and conventional refraction-diffraction model solutions. A proper treatment of discontinuities in the wave field (tips of breakwaters) would further improve the results.