Dynamic deformation of the floating collar of a net cage under the combined effect of waves and current

In this study, a numerical model was established to simulate the dynamic behavior of a floating net cage in waves and current, based on the finite element method. To validate the numerical model, we considered a case based on the motions of the net cage under regular waves and current, where we calculated and compared the simulated results. The comparison of the results indicated good agreement. We calculated the dynamic deformation of the floating collar of the net cage under regular/irregular waves and current, and we analyzed the effects of the net, strong waves and current, and the length of the mooring line on the cage collar deformation. The results indicated that the deformation of the floating collar with a net was much greater than that without a net. The collar deformation became larger as the wave height or current velocity increased. Therefore, in order to reduce the risk of local collar failure due to plastic deformation, adding a casing pipe in the position of the mooring line connection point on the floating collar could greatly enhance the bearing capacity of the cage collar under severe sea conditions. In addition, increasing the length of the mooring line would help to decrease the mooring line tension and further reduce deformation of the cage collar.