Hydrodynamic Simulation Using CFD (OpenFOAM) and Experimental Validation of a Point Absorber Wave Energy Converter

Abstract

This study presents a hydrodynamic simulation of a point absorber-type wave energy converter (WEC) with a single heave degree of freedom. The simulation was carried out using computational fluid dynamics (CFD) through the OpenFOAM software, under linear wave conditions and considered monochromatic waves to simplify the analysis of wave-body interactions. Due to OpenFOAM´s lack of native support for Octree-type mesh generation, a custom meshing strategy was developed in-house.This strategy combines polyhedral and hexahedral cells, reducing the total number of elements while maintaining high accuracy in critical regions, such as the vicinity of the buoy and the free surface. This optimization improved the simulation´s computational efficiency without compromising the quality ofthe results. To characterize the system´s hydrodynamic response, forced heave oscillation and regular wave excitation tests were conducted. These simulations enabled the estimation of the excitation force and derivation of the transfer function, which describes the buoy´s dynamic behavior. The numerical results showed good agreement with those obtained using the Boundary Element Method(BEM), which is commonly employed for wave-structure interaction problems. In addition to numerical comparisons, experimental validation was performed for both test cases. The experiments were conducted in the wave tank facility at the Faculty of Engineering, University of Buenos Aires, using instrumentation and testing equipment designed and built by our research group. Comparingthe numerical and experimental data confirmed the CFD model´s accuracy and applicability to the analysis and design of wave energy converters. The developed methodology provides a robust framework for future studies involving more complex sea states or device configurations.