Numerical simulation of the forces and deformation of HDPE circular gravity cages

The aim of this study is to comprehensively discuss the effects of cage perimeter, pipe diameter, net height as well as net mesh size on the forces and deformation of deep-water net cages in waves and current, thus provide references to select net-cages scientifically. We simulated HDPE cages with perimeter 40~80 m, pipe diameter 250~630 mm, net height 6~20 m and net mesh size 45~115 mm. With a numerical model previously validated by physical model tests, the mooring line forces, the wave-current forces and the volume reduction rate of the four kinds of HDPE cages are calculated. The simulated results indicate that the mooring line force and wave-current forceare greater while the volume reduction rate is smaller for bigger cage. Moreover, the mooring line force of cage could be greatly reduced by adding mooring lines. Compared to pipe diameter, net height and net mesh size have more significant impact on the cages force and deformation, which increase with net height increasing, while decrease with net mesh size increasing.