Numerical analysis of a fish cage in sea current considering fish net effect

This research applies a coupled Fluid–Structure Interaction (FSI) approach to investigate the hydrodynamic behavior and structural deformation of submerged cylindrical fish cages with flexible nets under varied flow velocities. To maximize computational efficiency without sacrificing accuracy, the computational model employs a mesh grouping technique. ANSYS Fluent and Static Structural simulations were conducted, and the results were validated against data from a full-scale sea test. With drag force predictions reaching a percent error as low as 1.03% at higher velocities, numerical findings demonstrate that using FSI method improves accuracy. Models with a mesh grouping factor (λ=40) yielded more precise deformation results compared to λ=80, with deformation errors ranging from 4.17% to 8.91%. Overall, the work shows that FSI modeling captures important fluid–net interactions that are frequently missed in simpler techniques, whereas the mesh grouping method efficiently lowers computational costs without significantly sacrificing accuracy. The analysis shows that lower λ values result in more accurate deformation predictions but demand higher computational resources. Recommendations for future work include studying the effects of various net materials, fish interactions, and dynamic wave loads to enhance fish cage performance under more complicated conditions.