CFD and FEA-based assessment of an oscillating underwater energy harvester for river flow energy harvesting

Abstract

This study investigates the numerical performance of an oscillating underwater energy harvester intended for hydrokinetic energy recovery in river flow environments. The analysed concept is based on an oscillating cylinder developed within the H-HOPE project and designed to convert flow-induced motion into usable mechanical energy. A combined Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) approach was applied to evaluate both the hydrodynamic response of the device and its structural behaviour under simulated operating conditions. The CFD results showed that cylinder diameter has a clear influence on the generated power. The 61 mm cylinder produced an average power output of 3.02 W, whereas the 49 mm cylinder generated 2.05 W, indicating a reduction of approximately 32% for the smaller configuration. The structural analysis showed that the maximum Von Mises stress remained below the yield strength of aluminium 6061, while the obtained safety factor of 2.10 confirmed the mechanical adequacy of the design under the analysed loading conditions. The results indicate that the proposed harvester has potential for small-scale river energy applications, particularly where compact and decentralized renewable energy solutions are required. However, further work should include fatigue assessment, fluid–structure interaction analysis and experimental validation under real river flow conditions.