WAVE AND CURRENT INTERACTIONS WITH OBSTACLES

Wave attenuation induced by aquatic vegetation is a key process in the development of nature‐Based Solutions (NbS) for sustainable coastal protection. Reliable prediction of vegetation‐induced wave energy dissipation is essential for the design of mangrove restoration projects, eco‐engineered barriers, and other nature‐based coastal defence systems. This study presents a coupled analytical–numerical framework for investigating the propagation of regular gravity waves through submerged rigid vegetation represented by arrays of cylindrical stems. The analytical model is derived from the conservation of wave energy by introducing vegetation‐induced drag through a bulk drag coefficient, providing a rapid prediction of wave‐height attenuation under different hydrodynamic and geometric conditions. The theoretical formulation is coupled with fully threedimensional simulations performed using the DualSPHysics solver based on the Weakly Compressible Smoothed Particle Hydrodynamics (WCSPH) approach and a Large Eddy Simulation–Sub‐Particle Scale (LES–SPS) turbulence model. The numerical model is first validated against laboratory measurements and subsequently employed to investigate the detailed flow dynamics within the vegetation canopy. Excellent agreement is achieved between the analytical predictions and the numerical simulations for all the configurations investigated. The numerical analyses reveal the formation of coherent antisymmetric vortical structures around submerged cylinders and demonstrate the significant influence of vegetation density, stem spacing, submergence ratio, and wave characteristics on both wave attenuation and the bulk drag coefficient. The proposed framework combines the computational efficiency of analytical formulations with the detailed flow description provided by high‐resolution SPH simulations, offering a practical engineering tool for the analysis, design, and optimization of Nature‐Based coastal protection systems.