Numerical Study on Internal and External Flow Fields of the UHMWPE Cage

Ultra-high molecular weight polyethylene (UHMWPE) is a new kind of fishing gear material applied in deep-sea fishing cages, which is becoming a trend. Studies on the internal and external flow fields of cages made of UHMWPE have been scarce previously. Therefore, a three-dimensional numerical model for the UHMWPE cage is established herein, where the cage is modeled by a porous media model. The Darcy–Forchheimer coefficients of the porous media are obtained by physical model experiments and numerical simulations. Then, the cylindrical cage is divided into 16 planar nets circumferentially, along with an additional bottom net, to investigate its internal and external flow fields numerically. For a single cylindrical cage, the degree of deceleration decreases as the flow velocity increases, and this effect becomes less apparent when the flow velocity reaches a certain threshold. Finally, the flow field characteristics of double cages with different spacing and multiple cages with equal spacing are revealed.