Experimental assessment and prediction of wave loading around abrupt depth transitions

Abrupt depth transitions cause significant changes in the characteristics of the wave field, increasing the non-linearity of the wave train and the likelihood of extreme events. The free surface elevation and wave kinematics exhibit different spatial behaviour depending on the local bathymetry. As a result, the critical location for wave loading cannot be identified from the free field properties alone. This study presents the results of a comprehensive experimental analysis of wave loading on a vertical cylinder around a shoal bathymetry. Extreme crest heights are most prevalent immediately downstream of the crest of the shoal, while extreme loads are found to be most frequent above the crest. However, this is influenced by the presence of wave breaking, which generates enhanced loading events of increased magnitude. The prediction of wave loading using Morison’s equation is investigated, with wave kinematics estimated using linear random wave theory and a numerical model (SWASH). The findings demonstrate the importance of the empirical inertia coefficient, which must reflect both the loading regime and the choice of kinematics model. • Experimental study of free field and wave loading behaviour around a shoal bathymetry. • Analysis of statistical changes in non-breaking and breaking sea states. • Investigation of force prediction using Morison’s equation, considering theoretical and numerical kinematics estimates.