Numerical simulation of parametric resonance in point absorbers using a simplified model

Adi Kurniawan*, Thanh Toan Tran, Scott A. Brown, Claes Eskilsson, Jana Orszaghova, Deborah Greaves

*Corresponding author for this work

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Abstract

Parametric resonance is a non-linear phenomenon in which a system can oscillate at a frequency different from its exciting frequency. Some wave energy converters are prone to this phenomenon, which is usually detrimental to their performance. Here, a computationally efficient way of simulating parametric resonance in point absorbers is presented. The model is based on linear potential theory, so the wave forces are evaluated at the mean position of the body. However, the first-order variation of the body's centres of gravity and buoyancy is taken into account. This gives essentially the same result as a more rigorous approach of keeping terms in the equation of motion up to second order in the body motions. The only difference from a linear model is the presence of non-zero off-diagonal elements in the mass matrix. The model is benchmarked against state-of-the-art non-linear Froude–Krylov and computational fluid dynamics models for free decay, regular wave, and focused wave group cases. It is shown that the simplified model is able to simulate parametric resonance in pitch to a reasonable accuracy even though no non-linear wave forces are included. The simulation speed on a standard computer is up to two orders of magnitude faster than real time.

Original languageEnglish
JournalIET Renewable Power Generation
Volume15
Issue number14
Pages (from-to)3186-3205
Number of pages20
ISSN1752-1416
DOIs
Publication statusPublished - 2021

Bibliographical note

Funding Information:
A.K. would like to acknowledge the support from the Wave Energy Research Centre, jointly funded by The University of Western Australia and the Western Australian Government, via the Department of Primary Industries and Regional Development. Part of this work was supported by the Danish Energy Agency under project number 64017‐05197. T.T.T. was funded by the U.S. Department of Energy, Water Power Technologies Office. This work was also authored in part by the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE‐AC36‐08GO28308. The views expressed in this article do not necessarily represent the views of the DOE or the U.S. Government. The publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a non‐exclusive, paid‐up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for U.S. Government purposes. S.A.B. and D.G. gratefully acknowledge the support from the Engineering and Physical Sciences Research Council (EPSRC), UK, through the Partnership for Research in Marine Renewable Energy (EP/P026109/1) and Supergen ORE Hub (EP/S000747/1) projects.

Publisher Copyright:
© 2021 The Authors. IET Renewable Power Generation published by John Wiley & Sons Ltd on behalf of The Institution of Engineering and Technology

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