Hydrodynamics of bio-mimetic sponge arrays with non-uniform triangular arrangement under wave actions

Bio-inspired marine structures have attracted increasing attention as nature-based solutions for modifying coastal hydrodynamics and enhancing momentum exchange. Previous studies on isolated and dual sponge-inspired elements have shown limited hydrodynamic effectiveness under relatively low-height waves, where velocity redistribution and turbulence generation remain weak. To address this limitation, the present study proposes and experimentally fabricates a bio-mimetic pillar coral composed of non-uniform triangular sponge elements arranged in a progressive three-line configuration. Numerical simulations were performed using OpenFOAM based on the Reynolds-averaged Navier–Stokes equations, coupled with the k–ω SST turbulence closure and the Volume of Fluid method. Advanced flow visualization techniques were further utilized to characterize vortex interactions and momentum redistribution mechanisms within the array. Results demonstrate that the proposed colony-scale arrangement substantially enhances inter-element hydrodynamic interactions and compensates for the weak performance of single sponge systems under waves with relatively low heights. Compared with the single-element configuration, the proposed arrangement increases mean phase velocity by approximately 2.5 times and turbulent kinetic energy by more than one order of magnitude while improving wave attenuation characteristics. The findings highlight the potential of non-uniform sponge colonies as engineered nature-inspired systems for coastal flow modification and ecological hydrodynamic enhancement.