Hydrodynamic response of artificial reefs to flow over irregular seabed

This study investigates the influence of seabed topography on the hydrodynamic performance of artificial reefs by incorporating a variable-bottom offshore bar. Numerical results show that positioning the reef in front of the offshore bar increases internal upwelling velocity compared to a no-bar scenario. The closer the reef is to the offshore bar, the stronger the upwelling within the reef structure. When the reef is placed behind the offshore bar, upwelling velocity increases; however, positioning it too close to the front results in a free surface elevation similar to the no-reef condition. Increasing the distance between the reef and the offshore bar further enhances wave dissipation. We also found that placing the reef in front of the offshore bar provides dual benefits: improved wave energy dissipation and better ecological performance. Additionally, increasing reef height intensifies flow field disturbance and significantly amplifies hydrodynamic forces, particularly when the D/h ratio exceeds 1.0. Thus, it is recommended that the D/h ratio remain at or below 1.0 to ensure structural stability and longevity. Finally, analysis of the offshore bar front slope indicates that slopes ranging from Z0/d = 1/2 to Z0/d = 1/1 achieve an optimal balance between upwelling velocity and structural loads.