Hydrodynamics and wave transmission through a hollow triangle breakwater

Abstract

Coastal protection, shoreline stabilization and mangrove forest restoration are pressing issues in such coastal regions worldwide as the Mekong Delta. A hollow triangle breakwater TC1 was developed to protect the coastline against erosion. The TC1 breakwater consists of holes arranged on the waveward and leeward sides, allowing for wave energy dissipation, water exchange, and sediment deposition to facilitate mangrove restoration. To evaluate comprehensively the working principles of the TC1, we investigate herein the wave-structure interaction under regular waves by means of an advanced computational fluid dynamics (CFD) platform, i.e. FLOW-3D. The numerical model was calibrated against experimental results with great agreement across three different water depths where the breakwater was tested. We also analyzed the velocity dynamics in the waveward and leeward sides of the breakwater and it revealed a significant difference of approximately 50% following the change in water depths from 0.66 m to 0.96 m. Furthermore, we examined the wave forces on both solid and hollow forms of TC1 structures, the wave forces on a hollow form were found to decrease by 20–30% in comparison with the forces on a solid form. In addition, the effect of liquid characteristics, i.e., density, viscosity and temperature showed slightly impact on wave transmission coefficients through the breakwater by 0.4–0.7 %.