Leveraging 2:1 Parametric Resonance in a Notional Wave Energy Harvester

In ocean engineering applications, parametric resonance is normally detrimental for the stability of large structures, so the vast majority of effort in the literature is toward preventing and reducing it; similarly, parametric excitation is usually undesired for wave energy extraction too, since it often reduces the conversion ability. Conversely, this chapter investigates the possibility to purposely introduce a 2:1 parametric resonance into a pitching wave energy harvester in order to inherently increase the energy absorption capabilities. Such a change in perspective is enabled by the use of a computationally efficient nonlinear hydrodynamic model (nonlinear Froude-Krylov force), which is able to articulate such a parametric instability at an early-development stage in a design-oriented simulation framework. The introduced 2:1 instability is found to be promising, since a significant amplification is obtained in the 2:1 region, where the oscillation amplitude is similar or even higher than in the 1:1 region.