WWM Extended to Account for Wave Diffraction on a Current Over a Rapidly Varying Topography

Abstract

The WWM (wind wave model) is extended to account for wave refraction-diffraction for wind waves propagating over a rapidly varying seabed in the presence of current. The wave diffraction effect is introduced into the wave action balance equation through the correction of wavenumber and propagation velocities using a diffraction corrected parameter. The approximation is based on the mild-slope equation for wave refraction-diffraction with current effect on a rapidly varying sea bottom. The relative importance of additional terms that influence the corrected diffraction parameter in the presence of currents was first introduced. The comparison of numerical results with other numerical models and experiments show that the validity of the model for describing wave propagating over a rapidly varying bottom with current effect is satisfactory. The implementation of this phase-decoupled refraction-diffraction approximation in WWM shows capability of the present model can be used in most practical engineering situations.