This paper presents experimental and numerical studies into the hydrodynamic loading of a bottom-hinged large buoyant flap held rigidly upright in waves. Possible applications and limitations of physical experiments, a linear potential analytical method, a linear potential numerical method, a weakly non-linear tool and RANS CFD simulations are discussed. Different domains of applicability of these research techniques are highlighted considering the validity of underlying assumptions, complexity of application and feasibility in terms of resources like time and computing power needed to obtain results. Conclusions are drawn regarding the future extension of the numerical methods to the case of a moving flap.
Bottom hinged Oscillating Wave Surge Converters (OWSCs) are an efficient way of extracting power from ocean waves. The Oyster® wave energy converter developed by Aquamarine Power Ltd. is designed to operate in the near-shore region of 10 – 15m water depth. It consists of a large buoyant flap, hinged at the seabed, and completely penetrates the water column. The flap oscillates back and forth under wave action and drives the moving ends of hydraulic cylinders pushing high pressure water via a subsea pipeline to drive a conventional hydro-electric turbine (Cameron et al.; 2010). An analogy may be made between the flap oscillating in shallow water waves and some devices implemented for flood protection (Mei et al.; 1994). However, the design optimisation to maximize power output differs considerably. Since its development as a wave energy converter by Aquamarine Power Ltd. began in 2001, researchers have applied different experimental and numerical methods to investigate the underlying hydrodynamics to optimize the design and achieve a commercial cost of power. Compared to ships or other common offshore structures challenges still exist surrounding issues like the influence of shape variations, the role of viscosity, application of scaling laws and the distortions due to wave tank effects.
