Hydroelastic Buckling Analysis of a Novel Fish Pen

Abstract Offshore fish farming offers several advantages over nearshore environments, such as access to larger, less disturbed areas, improved water quality, and reduced prevalence of parasites and pathogens harmful to fish. However, the structural integrity of aquaculture infrastructure in offshore environments faces significant challenges from more severe waves and current conditions. To address these challenges, Blue Economy CRC has proposed an innovative offshore fish pen design, the SeaFisher. This modular structure uses bundled HDPE (high-density polyethylene) pipes for its frame, ensuring durability in seawater. Top longitudinal ballast pipes enable the SeaFisher to submerge during storms, avoiding strong surface waves. However, the flexible HDPE material introduces hydroelastic deformation under wave and current forces, potentially leading to hydroelastic buckling due to compressive stresses in the pipes. This paper presents the hydroelastic analysis of a numerical model construct based on SeaFisher design under various wave and current conditions. Using the finite element software AquaSim, the study evaluates the compressive axial forces in the structure’s components and determines its hydroelastic buckling capacity based on buckling safety factor results. A parametric study further explores the Fish pen’s behaviour under varying wave heights and frequencies. The findings reveal that increased wave heights and lower wave frequencies elevate the risk of buckling. These insights provide valuable guidance for optimizing the design and performance of offshore fish pens.