Impact of artificial reef configuration on wave dynamics and shoreline protection

Artificial reefs (ARs) are a promising solution against coastal erosion, as they effectively dissipate wave energy while providing ecological benefits. The present study investigates the influence of AR deployment on wave propagation and attenuation, using a three-dimensional numerical model based on the Navier–Stokes equations. A large-eddy simulation approach is employed, together with a porous-media formulation to model flow within the reef units. Reef-Ball type ARs are examined under regular wave conditions, with emphasis on how their spatial configuration affects wave attenuation. Τhe results indicate that introducing a single row of ARs leads to a measurable reduction in wave energy downstream of the reef field, whereas the deployment of two rows further enhances wave attenuation and delays wave breaking. Furthermore, the effects of streamwise and spanwise spacing between ARs were examined. Wave attenuation remains effective only when the streamwise spacing between successive rows is relatively small. When the streamwise spacing increases to approximately half a wavelength, the rows behave largely independently, leading to increased wave transmission. Variations in spanwise spacing have a less pronounced effect, although larger distances between units still result in reduced wave dissipation. The numerical findings provide practical guidance for optimising AR layouts to maximise coastal protection performance.