Bingham, Harry and Yu, Yi-Hsiang and Nielsen, Kim and Tran, Thanh Toan and Kyong-Hwan, Kim and Park, Sewan and Hong, Keyyong and Said, Hafiz Ahsan and Kelly, Thomas and Ringwood, John and Read, Robert and Ransley, Edward and Brown, Scott and Greaves, Deborah (2021) Ocean Energy Systems Wave Energy Modeling Task 10.4: Numerical Modeling of a Fixed Oscillating Water Column. Energies, 14 (1718). ISSN 1996-1073

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Abstract

This paper reports on an ongoing international effort to establish guidelines for numerical modeling of wave energy converters, initiated by the International Energy Agency Technology Collaboration Program for Ocean Energy Systems. Initial results for point absorbers were presented in previous work, and here we present results for a breakwater-mounted Oscillating Water Column (OWC) device. The experimental model is at scale 1:4 relative to a full-scale installation in a water depth of 12.8 m. The power-extracting air turbine is modeled by an orifice plate of 1–2% of the internal chamber surface area. Measurements of chamber surface elevation, air flow through the orifice, and pressure difference across the orifice are compared with numerical calculations using both weakly-nonlinear potential flow theory and computational fluid dynamics. Both compressibleand incompressible-flow models are considered, and the effects of air compressibility are found to have a significant influence on the motion of the internal chamber surface. Recommendations are made for reducing uncertainties in future experimental campaigns, which are critical to enable firm conclusions to be drawn about the relative accuracy of the numerical models. It is well-known that boundary element method solutions of the linear potential flow problem (e.g., WAMIT) are singular at infinite frequency when panels are placed directly on the free surface. This is problematic for time-domain solutions where the value of the added mass matrix at infinite frequency is critical, especially for OWC chambers, which are modeled by zero-mass elements on the free surface. A straightforward rational procedure is described to replace ad-hoc solutions to this problem that have been proposed in the literature.

Item Type:	Article
Additional Information:	Funding: KN and the DTU team gratefully acknowledge the support of the Danish Energy Agency, EUDP grant numbers 64017-05197 & 64020-1105. NREL was funded by the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy Water Power Technologies Office under Contract DE-AC36-08GO28308. JR and HAS were, in part, supported by Science Foundation Ireland under Grant 13/IA/1886. © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). Cite as: Bingham, H.B.; Yu, Y.-H.; Nielsen, K.; Tran, T.T.; Kim, K.-H.; Park, S.; Hong, K.; Said, H.A.; Kelly, T.; Ringwood, J.V.; Read, R.W.; Ransley, E.; Brown, S.; Greaves, D. Ocean Energy Systems Wave Energy Modeling Task 10.4: Numerical Modeling of a Fixed Oscillating Water Column. Energies 2021, 14, 1718. https://doi.org/10.3390/en14061718
Keywords:	wave energy; experimental measurements; numerical modeling; simulation; boundary element method; computational fluid dynamics;
Academic Unit:	Faculty of Science and Engineering > Research Institutes > Centre for Ocean Energy Research Faculty of Science and Engineering > Electronic Engineering
Item ID:	14350
Identification Number:	https://doi.org/10.3390/en14061718
Depositing User:	Professor John Ringwood
Date Deposited:	19 Apr 2021 15:16
Journal or Publication Title:	Energies
Publisher:	MDPI AG
Refereed:	Yes
Funders:	Danish Energy Agency (EUDP), U.S. Department of Energy Office of Energy Efficiency and Renewable Energy Water Power Technologies Office, Science Foundation Ireland (SFI)
URI:	Publisher
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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