Comparative study of circular and square gravity-based fish cages with different dimensions under pure current conditions

Abstract

Two typical gravity-based fish cages with circular and square shapes are modeled in the present study to compare their cage deformations, cultivation volumes and drag forces under different pure current conditions. Two hy drodynamic models, i.e., Morison model and Screen model, are implemented into a general finite element (FE) solver Code_Aster as a new module and employed in the dynamic analyses of the fish cages. Different cage dimensions (i.e., circumferences and design heights) and current velocities are considered in the comparative study. The numerical results indicate that given the same area of netting, the circular cage can gain more cultivation volume than the square cage, especially when the initial cage volume is larger than 100,000 m3. The square cage has a slightly larger drag force per cultivation volume than the circular cage. This study suggests that the circular cage is superior to the square fish cage for large-scale fish farms.