Applying direct numerical simulations to investigate wave forcing against a vertical wall

Current engineering standards lack the ability to predict the peak impact forces of breaking waves impinging directly upon coastal structures. In this study solitary waves impacting vertical and tapered walls are investigated. To capture the detailed physics of the wave profile that impacts the wall, two-dimensional direct numerical simulations are applied to model the wave traveling over a simplified bathymetry consisting of an initially uniform depth, followed by a uniform beach ramp and then terminating in a uniform depth inshore region and vertical wall. Such an approach can simulate wave runup on land and then the impact with the vertical or tapered walls. The wall location in the bathymetry was varied to simulate different types of wave impacts, including non-breaking, plunging, and bores. The resulting wave characteristics and wall impact pressures were compared across these varying regimes. The associated wave impact force was extracted and compared to various standards used in coastal engineering, and severe underestimation has been found for plunging and weak plunging type impacts. To address this, in this study, a dimensionless distance parameter has been proposed to provide a unifying trend in regards to the peak impact forcing across the various impact types.