Hydrodynamic Analysis of Aquaculture Net Cages Under Coupled Netting-Fish-Sediment Interactions

To address the limitations of existing studies that neglect sediment feedback and thus underestimate the complexity of the flow field, this study develops a three-dimensional hydrodynamic model for aquaculture cages that couples a porous-media representation of netting with a two-way discrete-phase model for sediment transport. Unlike traditional single-factor simulations, this work systematically evaluates three interaction scenarios: netting-only, netting-fish coupling, and netting-fish-sediment multi-factor coupling, thereby revealing key nonlinear hydrodynamic mechanisms that have not been reported before. The results demonstrate that sediment particles induce a distinct momentum-feedback-driven “local re-acceleration zone” downstream of the cage, increasing turbulent kinetic energy by 13.2% and reducing wake velocity attenuation by 6-8%. These findings confirm that sediment–fish–netting interactions significantly modify wake shear structures and must be accounted for to ensure accurate flow prediction. This study provides new mechanistic insights into multi-factor hydrodynamics and a refined modeling framework to optimize cage design, enhance water exchange, and support sediment management in intensive mariculture.