Hydraulic performance of Cubipod Homogeneous Low Crested Structures in depth-limited wave breaking conditions

This study presents a comprehensive investigation into the hydraulic stability and wave transmission of Cubipod Homogeneous Low-Crested Structures (HLCS) placed on a rocky seabed in depth-limited wave breaking conditions. Cubipod HLCS are designed to recover degraded coral reef areas. 2D small-scale physical tests were conducted to evaluate wave transmission and damage of trunk and head sections with two placement grids: Square Placement Grid (SPG) and Triangular Placement Grid (TPG). A method based on Artificial Neural Networks (ANN) and bootstrapping was used to rank the governing physical variables on damage and wave transmission. New empirical formulas are proposed to estimate damage and wave transmission of Cubipod HLCS showing good agreement with observations (R 2 > 0.79). Damage was highly sensitive to the power stability number, = H m0 4/5 L 0p 1/5 /(ΔD n ), and relative freeboard ( R c /D n ), indicating that emerged structures suffer greater damage. The SPG layout showed higher hydraulic stability than TPG for trunk and head sections, and similar transmission performance. Wave transmission was dependent on the initial crest freeboard and deepwater wave steepness with no significant dependence on accumulated damage. A design procedure and a desk application are given to illustrate how to apply the recommendations in designing Cubipod HLCS in depth-limited wave breaking conditions.