Abstract
This manuscript reviews experimental scour investigations with reference to a recent Oscillating Water Column (OWC) Wave Energy Converter (WEC) deployment, in addition to presenting preliminary numerical results for scour potential around large caissonlike structures, similar to an OWC WEC. Previous research on OWC WEC’s has focused mainly on the energy efficiency or internal flow patterns, with limited understanding of potential scour behaviour. Despite this, large scale OWC WECs have significant scour potential due to the complex interactions of highly energetic wave climates with the bluff body structure and alternating inflow/ outflow of water within the device. The wave-seabed-structure interactions contribute to increased sediment motion due to the potential formation of leewake vortices and wave reflection/ diffraction effects. Besides environmental impacts that need to be quantified, scour around an OWC WEC has the potential to directly affect the structures stability, and create settlement issues which in turn can lead to compromised device performance and further deterioration of structure stability. It is likely that for future investigations of scour potential around OWC WEC’s, project-specific numerical or experimental investigations will be required to enable optimisation of the device geometry and test design innovations for scour reduction. Preliminary results using the open-source CFD REEF3D model are presented showing scour development around a caisson-like box structure. Utilising the Smagorinsky Sub-grid Scale (SGS) turbulence model, results are shown to compare well with previous experimental measurements, however fundamentally different scour patterns form when the Reynolds-Averaged Navier-Stokes (RANS) k-ω turbulence model is used. Understanding the (in)ability of CFD models to represent the relevant physical processes is therefore critical to the development of the OWC WEC industry.