Hydrodynamic analysis and optimization of a floating wave energy converter with moonpool using OpenFOAM®

This paper presents the hydrodynamic analysis and optimization of a novel axisymmetric single cylindrical Wave Energy Converter (WEC) equipped with a Moonpool, called MoonWEC. The primary aim of the study is to optimize the design of the MoonWEC by minimizing pitch rotations, enhancing heave motion, and facilitating moonpool oscillations. A set of new laboratory experiments was conducted to characterise the hydrodynamic response of the MoonWEC. These experiments were reproduced using a Numerical Wave Tank (NWT) in OpenFOAM. Qualitative and quantitative data were recorded, and the heave and pitch response was analysed by comparing experimental and numerical data. Good agreement between experimental and numerical data was observed throughout all the simulations. The results showed that the MoonWEC device can achieve the preferred excitation in heave, but it can also undergo the unpreferred excitation in pitch. By shifting the centre of mass, MoonWEC was numerically optimized to reduce the pitch rotations without affecting the heave oscillations. The moonpool motion was also analysed for the optimised prototype. The study shows that the CFD model in OpenFOAM coupled with the MooDy library can be used to simulate the hydrodynamics of the MoonWEC accurately. The optimization study shows that the centre of mass of the device is a key parameter in controlling the natural period of the device in pitch. The analysis of the moonpool shows that the MoonWEC has the potential to generate significant power.