Numerical analysis of wave–structure interaction of regular waves with surface-piercing inclined plates

C. P. Cummins, G. T. Scarlett, C. Windt

Research output: Contribution to journalArticlepeer-review

Abstract

The Mocean wave energy converter consists of two sections, hinged at a central location, allowing the device to convert energy from the relative pitching motion of the sections. In a simplified form, the scattering problem for the device can be modelled as monochromatic waves incident upon a thin, inclined, surface-piercing plate of length L in a finite depth d of water. In this paper, the flow past such a plate is solved using a Boundary Element Method (BEM) and Computational Fluid Dynamics (CFD). While the BEM solution is based on linear potential flow theory, CFD directly solves the Navier–Stokes equations. Problems of this type are known to exhibit near-perfect reflection (indicated by a reflection coefficient | R| ≈ 1) of waves at specific wavenumbers k . In this paper, we show that the resonant motion of the fluid induces large hydrodynamic forces on the plate. Furthermore, we argue that this low-frequency resonance resembles Helmholtz resonance, and that Mocean’s device being able to tune to these low frequencies does not act like an attenuator. For the case where the water is deep (d > λ / 2 , where λ = 2 π/ k ), we find excellent agreement between our simulations and previous semi-analytical studies on the value of the resonant wave periods in deep water. We also find excellent agreement between the excitation forces on the plate computed using the BEM model, analytical results, and CFD for large inclination angles (α> 45 ). For α≤ 15 , both methods show the same trend, but the CFD predicts a significantly smaller peak in the excitation force compared with BEM, which we attribute to non-linear effects such as the non-linear Froude–Krylov force.

Original languageEnglish
JournalJournal of Ocean Engineering and Marine Energy
Early online date22 Nov 2021
DOIs
Publication statusE-pub ahead of print - 22 Nov 2021

Keywords

  • BEM
  • CFD
  • Inclined plate
  • Reflection coefficient
  • Wave energy conversion

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Water Science and Technology
  • Energy Engineering and Power Technology
  • Ocean Engineering

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