A CFD Study on the Balance of Energy in a Fixed Bottom-detached Oscillating Water Column Wave Energy Converter

In this work, a 3D Computational Fluid Dynamics (CFD) model of a fixed, bottom-detached Oscillating Water Column (OWC) is used to investigate the energy balance for the device. The numerical model is implemented in the open source OpenFOAM® environment. The CFD model is validated against laboratory tests, in order to prove the model capability to reproduce the flow field and the hydrodynamics of the device. Applying the energy conservation principle and considering the overall energy balance for the OWC, it is possible to clearly define the total energy losses taking place in the device because of, e.g., wave breaking, viscous, turbulence and vortex losses at the front wall lip. The energy losses corresponding to different design parameters are comparatively analysed, giving an insight on the physics involved in the losses phenomenon and on the design conditions leading to the highest hydrodynamic efficiency.