Hydroelasticity analysis of a vessel-shaped fish cage under incident, diffraction and radiation wave fields

Abstract

Vessel-shaped fish cages are promising large aquaculture structures developed in recent years, with an overall length of nearly 400 m. In this paper, a coupled hydroelasticity model of a vessel-shaped fish cage is used to calculate the motion and structural response in the time domain. First, the floating body of the cage is discretized into a multimodule system to calculate the frequency-domain hydrodynamic loads. Then, the multimodule system is connected by equivalent elastic beams to consider the hydroelastic behavior in the time domain. The hydrodynamic loads of the multimodule system are transformed from the frequency-domain loads. Moreover, based on the velocity field transfer functions and the motion of the multimodule system, coupling wave fields considering incident, diffraction and radiation waves are built and used to calculate the loads on the net and steel frame. By iterating the motion response of the multimodule system and the hydrodynamic loads on the net and steel frame in the time domain, the balanced hydroelasticity response of the whole cage is finally obtained. The results show that the hydroelasticity effects have a significant influence on the vertical displacement and cross-sectional load effects of the vessel-shaped fish cage.