Transformation of wave skewness and asymmetry over low-crested breakwaters

This paper presents the results of an investigation of wave asymmetries to understand the processes in the interactions between waves and low-crested breakwaters, (LCBs), based on an analysis of measurements collected in the DELOS project. Considering the effect of Ursell number and relative freeboards of LCBs on wave asymmetries, a set of empirical formulae was established, using least squares regression. We found that wave skewness retains a positive sign on both sides but wave asymmetry changes from negative value on the incident side to positive value on the transmission side. Although relationships between wave asymmetries and Ursell number for smooth breakwaters are similar to those for rubble mound breakwaters, the effect of relative free boards on the former is less significant than that on the latter.