MODELLING NONLINEAR SHORT-WAVE GROUPS AND INFRAGRAVITY WAVES IN PHASE-RESOLVED SIMULATIONS

Infragravity waves are long waves with typical period greater than 30 seconds. They are induced by the grouping of short waves, and they are bounded to the groups in open sea. After they arrive at the nearshore region, they can be released and become free waves. The generation of the free long waves can be due to abrupt change of bathymetry, wave breaking and so on. This study presents a computationally efficient numerical wave model for simulating wave groups and the underlying infragravity waves simultaneously in phase-resolved approach. The new model is based on the potential flow theory and the boundary integral equation (Fructus and Grue, 2007) with a new set of formulations and a successive approximation scheme for estimating the surface vertical velocity considering the water depth variability.