RIASSUNTO
Knowledge of the hydrodynamic behavior of a net cage under the action of waves and currents is the basis of the design and management of net cages in the open sea. Techniques used to investigate the net cage have typically included the use of scaled physical and numerical models, and, where possible, field measurements. Comparing model tests and field measurements, the numerical simulation method is low in cost, easy to manage and a time-saver. In this paper, a numerical model has been developed by rigid body kinematics and the lumped mass method to investigate the dynamic response of the gravity cage in current and waves. Using the numerical model, the motion, net deformation and mooring line forces of the gravity cage were calculated under current only, waves only and combined wave and current flow, respectively. A series of physical experiments was carried out to evaluate the validity of the numerical model. The results of our numerical simulation are all in close agreement with the experimental data. This study shows that our model is valid for the simulation of the net cage in current and waves.
INTRODUCTION
Exposed net cages in the open sea are subjected to wave and current action. From an engineering perspective, net cage systems need to be designed to cost-effectively withstand extreme conditions while providing a suitable growing environment. Thus, knowledge of their hydrodynamic behavior under the action of waves and currents is important for the design and management of net cages in the open sea. The main methods used to investigate the net cage have typically included the scaled physical tests, numerical simulation and, where possible, field measurements. Many research studies have been conducted to better predict the dynamic performance and reliability of the net cage while subjected to wave and current forces.