Abstract In this study, we numerically investigated the drag force and deformation characteristics of a closed flexible membrane fish cage subjected to uniform flow. The target fish cage is circular, representing a real cage with dimensions of 25 m in diameter, a sheet height of 12.5 m, and a freeboard of 2.5 m. A 1/50 scale model was employed for numerical simulations. The numerical result was validated against experimental data from previous studies. Simulations were conducted at flow velocities ranging from 5 to 25 cm/s, with 5 cm/s intervals, under different filling rates to evaluate the drag force and deformation of the flexible cage. The results were also compared with those from traditional flexible net cages of the same dimensions. As a result, consistent with existing experimental findings, the flexible membrane fish cage did not exhibit large deformations like net cages. However, as the filling rate decreased, the deformation of the flexible structure became more pronounced. The deformation of the front membrane was more significant than that of the rear membrane. Additionally, drag force was observed to increase with flow velocity, consistent with prior research. Notably, the drag force on the flexible membrane fish cage was approximately several times greater than that on net cages. The study also provided a detailed tension distribution across the entire membrane fish cage. Overall, these results are expected to serve as valuable references for the design and operational optimization of closed flexible membrane fish cage systems, contributing to the advancement of sustainable aquaculture practices.
Dong et al. (Sun,) studied this question.