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

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 param...

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Bibliographic Details
Published in:	IET renewable power generation Vol. 15; no. 14; pp. 3186 - 3205
Main Authors:	Kurniawan, Adi, Tran, Thanh Toan, Brown, Scott A., Eskilsson, Claes, Orszaghova, Jana, Greaves, Deborah
Format:	Journal Article
Language:	English
Published:	United Kingdom Institution of Engineering and Technology (IET) 01.10.2021 Wiley
Subjects:	Applied fluid mechanics Fluid mechanics and aerodynamics (mechanical engineering) Function theory, analysis General fluid dynamics theory, simulation and other computational methods Numerical approximation and analysis Surface waves, tides, and sea level
ISSN:	1752-1416, 1752-1424
Online Access:	Get full text
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Summary:	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.
Bibliography:	USDOE
ISSN:	1752-1416 1752-1424
DOI:	10.1049/rpg2.12229