A HYBRID METHOD TO COMBINE WAVE PENETRATION AND LOCAL WAVE GROWTH IN LARGE HARBOR BASINS

Abstract

This paper describes a hybrid method to determine the wave conditions in large harbor basins were wave propagation and local wave growth by wind are both of relevance. The method was developed to include the effects of diffraction and wind wave growth in the assessment of design wave conditions that so far cannot be computed within one wave model. The diffraction effects are computed with a phase-resolving wave penetration model, and the wind effect is computed with a phase averaged spectral wave model. The method accounts for the effect the local wind wave growth occurs on top of the penetrating wave field. To isolate the wind wave growth, two model runs are performed with the phase-average model. One run includes wind forcing, whereas in the other run wind forcing is switched off. Subtracting the results of both methods isolates the local wave growth. The method is illustrated with a hypothetical example for the Port of IJmuiden, located along the North Sea coast of the Netherlands. In addition, an overview is given of the physical processes relevant for the determination of design wave conditions in large harbor basins. The assumptions of the hybrid method are discussed and recommendations are given for further improvements.