Fluid-structure interaction (FSI) modelling of aquaculture net cage

Abstract

The number of good sites for aquaculture farming in less exposed locations is limited. The trends now are that fish cages are increasing in both width and depth, as well as being used in more weather-exposed locations. As the net cages increase in size, so does the material costs. The design of the sea cages should be modified for safe and reliable use in remote offshore locations. Fish farms located in more exposed areas will be subject to more energetic waves and stronger currents, which will cause large net deformations. This is a challenge because fish welfare depends on a certain minimum volume within the net cage. Changing and maintaining net cages are some of the main expenses for fish farms. If the lifetime of the net cages is extended by introducing stronger, longer lasting materials, the overall costs of the nets can likely to be reduced. The traditional nets are produced using nylon, but promising solid PET-wire designs have also been introduced to the aquaculture industry. In this paper, we investigate the use of polyurethane in aquaculture net cages, which is studied together with nylon and PET-wire. The study is carried out using fluid-structure interaction (FSI) simulation, computational fluid dynamics (CFD) weakly coupled with structure mechanics (FEM). ANSYS® software is employed in the study. We will look at the materials that show the most promising results for aquaculture purposes.