Mechanism of wave-induced flow in reshaping breakwaters

This study aims to investigate the reshaping mechanisms of a reshaping berm breakwater by assessing the results of a 2D numerical model developed in OpenFoam®. The flow inside and outside the porous breakwater is numerically simulated. The initial and reshaped form of the breakwater is modelled using the Darcy-Forchheimer equation and k-ε closure models. The numerical model is calibrated with and validated against the experimental data of wave-induced pressure and water level fluctuations inside and outside the porous breakwater. Both initial and reshaped berm breakwater are assessed for calibration and validation processes. The result demonstrates that the minimum run-down level on the breakwater slope is a critical area in armor instability due to the outward driving forces; these forces are because of synchronizing excess pressure gradient and outward flow critically. Moreover, a parallel downward flow occurs during waves running down and can push the displaced armor down the slope. After reshaping, the breakwater profile has a milder slope than the initial profile and the outward forces due to excess pressure gradient is reduced to less than one-half of its initial amount due to the change in breaker type. As a result, the reshaped profile is modified to harmonize with new environmental conditions in the reshaping berm breakwater.