Parametric study of an undulating plate in a power-extraction regime

Our previous studies suggest that instead of propulsion, a body undergoing lateral traveling-wave-like motions can also work like a kinetic energy harvester which extracts energy from moving fluids including wind and water currents. Parameters including wavelength, dimensionless wave velocity and amplitude have critical effects on the energy extraction efficiencies of this type of undulating foil energy harvester. In this paper, a two-dimensional, numerical simulation of a flexible plate undergoing a traveling wave motion was then conducted. At a given dimensionless wave speed, it is found that there exits an optimum wavelength at which this type of energy harvester can extract the maximum amount of kinematic energy from the flow. Moreover, the optimum value of the wavelength increases as amplitude increases. A high efficiency area appears under the optimal combination of wavelength and amplitude. At a given amplitude, the optimal dimensionless wave speed for maximum power extraction decreases with increasing wavelength. The high efficiency area of the undulating plate resulting from the optimal combination of wavelength and wave speed is identified. At a given wave length, there is an optimal value of amplitude at which the maximum energy extraction can be achieved. In this case, a high efficiency area representing the optimal combination of amplitude and wave speed has also been discovered.