Wave Tank Testing of Optimized Artificial Reef Structures to Enhance Wave Energy Dissipation and Protect Coastlines

Increasing frequency and intensity of coastal storms, coupled with rising sea levels, has created a pressing need for innovative solutions to mitigate coastal erosion and preserve shoreline ecosystems. One such solution is artificial reefs; man-made structures installed along shorelines that mimic natural coastal reefs' wave energy dissipation function and provide habitat for marine life. Previous work at MIT has included Bayesian optimization of modular artificial reef units with high drag coefficients to dissipate wave energy effectively while attempting to minimize ecological disruption. These designs prioritize hydrodynamic performance while ensuring that they do not inhibit marine life in the same way conventional breakwaters do. This study experimentally evaluates the energy dissipation of these optimally designed artificial reef structures, testing scaled-down models under controlled wave conditions using the Bretschneider spectrum. Measurements include wave heights recorded upstream and downstream of the reef structures to quantify energy dissipation with two sets of wave conditions and comparing wave energy dissipation effects with single-frequency tests from prior work. Results indicate that multi-pillar reef structures with varying pillar angles develop reductions in wave energy density of 37 % to 50 %, quantified through reductions in wave height for transmitted waves. Future work includes refining reef geometries based on experimental findings and validating results in larger wave tanks and field deployments to guide full-scale implementations.