An investigation on the vibrations of a flexible net excited by irregular waves and irregular boundary deformations

Abstract

Aquaculture cages located in offshore areas typically contain frames and flexible nets. The cages are typically subjected to irregular waves and the frames may deform irregularly over time. Since the nets are tied on the frames, when the frames deform over time, the boundaries of the nets change. In this study, a large flexible net subjected to irregular waves and irregular boundary deformations is theoretically simulated. The irregular waves are simulated using the modified Jonswap spectrum, while the irregular boundary deformations are described by superimposing a series of cosine functions that follow a Gaussian distribution. The dynamic responses of a flexible net are solved numerically. The proposed model is validated by comparison with experimental results. When the boundaries of the net irregularly deformed in the vertical direction, the vibrations of the net in the vertical direction are significantly affected, while the vibrations in the horizontal direction are slightly affected, which are mainly dominated by irregular waves.