Influence of a tapered and slender wave collector on the increment of the efficiency of an oscillating water column wave-energy converter

The objective of this work is to analyze the effect of a tapered and slender wave collector, which follows a power law distribution, on the increment of the useful power and the efficiency of an oscillating water column wave-energy converter. The governing equations are solved by a numerical procedure. The forced motion of the oscillating water column by the linear long water waves is modeled via the implementation of a well-known energy equation. Applying the Reynolds transport theorem to the first law of thermodynamics, a conjugated hydrodynamic model of the gauge pressure in the open air chamber and the oscillating water column is derived. An asymptotic solution for the elevation of the water waves in the wave collector is obtained. The results show that compared with a system without a tapered wave collector, the tapered wave collector improves the capture efficiency and increases the useful power of the oscillating water column. The results suggest that large values of the oscillating water column can be obtained near resonance, a condition reached by the increment of the immersion of the front wall of the device for a fixed wavelength. The numerical solution is compared with the analytical solution of a linear oscillator.