Numerical simulation of a flatfish cage system in waves and currents

• A finite element model is developed to study the behavior of a flatfish cage system.
• The pith and mooring line tension of the flatfish cage in waves and currents are calculated.
• The effect of netting mesh types on behavior of the flatfish cage is investigated.
• The effect of different bottom frame weight on pitch of the flatfish cage is analyzed.

The hydrodynamic behavior of a flatfish cage system in waves and currents is investigated using a simulation model based on the finite element method. A series of scaled physical model tests are conducted to verify the numerical model. The maximum pitch of the bottom frame and mooring line tension of the cage are analyzed. The comparison results show that the simulated and the experimental results agree well. The motion process of the whole cage system in waves and currents can be described with the computer visualized technology. We find that the maximum pitch of the bottom frame is about 9° at a current of 26 cm/s. We conclude that the pitch and mooring line tension of flatfish cage increase with increasing wave height and wave period. Furthermore, the mooring line tension and pitch of the bottom frame with two mesh types are calculated under different current conditions. We recommend that the square mesh should be used to reduce the inclination of the cage. Finally, according to the numerical results, the maximum pitch of the bottom frame decreases with the increase of bottom frame weights.