Simulation modeling of the Adjustable Buoyancy Device for open ocean low trophic aquaculture, part I: Test of a submersible long tube unit

Abstract

Open‐water low‐trophic aquaculture (LTA) is a sustainable method for producing ocean‐based food and providing ecosystem services. An effective system design is critical for mitigating risks posed by deep ocean forces. Developing submersible cultivation technology requires quantitative risk analysis and modeling to address offshore challenges while ensuring sustainability and efficiency. This paper presents a numerical model developed using OrcaFlex software to simulate the Adjustable Buoyancy Device (ABD) technology for cultivating LTA species. The ABD multi‐body system includes a submersible Long Tube Unit (LTU), pulley, buoy, cultivation dropper line, and pulley rope anchored to the seabed and interacting hydromechanically in the open sea. The submersible LTU consists of eight internal units filled with either air or water to regulate its depth of submersion. The system was tested using North Sea meteorological data, high‐energy waves, and environmental loads from currents. A First Principal Multi‐Physics analysis was employed to derive the key parameters for the model. OrcaFlex was used to evaluate the system's performance under various conditions. Simulation results indicated that a wave force of 180° combined with a current direction of 90° and a maximum depth of 12–15 m was optimal for the system. The tensions at the LTU ends, labeled A and B, were recorded as 2.65 and 2.15 kN, respectively. The LTU wall and effective tension remained aligned throughout the simulation. The model was validated through theoretical calculations and statistical analysis.