| Description |
1 online resource (14 pages) : color illustrations. |
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text txt rdacontent |
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computer c rdamedia |
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online resource cr rdacarrier |
| Series |
NREL/CP ; 5000-77014 |
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Conference paper (National Renewable Energy Laboratory (U.S.)) ; 5000-77014.
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| Note |
"April 2021." |
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"Presented at 3rd International Offshore Wind Technical Conference (IOWTC2021) February 16-17, 2021." |
| Bibliography |
Includes bibliographical references (pages 12-13). |
| Type Of Report |
Conference paper. |
| Funding |
National Renewable Energy Laboratory DE-AC36-08GO28308 |
| Note |
Description based on online resource; title from PDF title page (NREL, viewed on Aug. 24, 2021). |
| Summary |
The natural surge and pitch frequencies of semisubmersible offshore wind platforms are typically designed to be below the wave frequencies to avoid direct excitation. However, surge or pitch resonance can be excited by the nonlinear low-frequency loads generated by irregular incident waves. Second-order potential-flow models with added Morison drag have been found to underpredict this low-frequency excitation and response. As part of the OC6 project, Computational Fluid Dynamics (CFD) simulations were performed to enable a better understanding of the low-frequency loads and the limitations of lower-fidelity models. The focus of the current paper is to set up a computationally cost-effective CFD simulation of a fixed semisubmersible platform to investigate nonlinear difference-frequency loads and establish the corresponding uncertainty in the results. Due to the high computing cost, CFD simulations of irregular waves can be challenging. Instead, simulations were performed with bichromatic waves having a shorter repeat period. A preliminary comparison with Quadratic Transfer Functions from second-order potential-flow theory shows that CFD models consistently predict higher nonlinear wave loads at the difference frequency, likely due to flow separation and viscous drag not accounted for in potential-flow theory. |
| Subject |
Computational fluid dynamics.
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Wind turbines -- United States.
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Dynamique des fluides numérique.
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Éoliennes -- États-Unis.
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Computational fluid dynamics
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Wind turbines
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United States https://id.oclc.org/worldcat/entity/E39PBJtxgQXMWqmjMjjwXRHgrq
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| Indexed Term |
2nd order |
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bichromatic waves |
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CFD |
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computational fluid dynamics |
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difference frequency |
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IEA wind |
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low frequency |
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OC6 |
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QTF |
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semisubmersibe |
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wave load |
| Genre/Form |
technical reports.
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Technical reports
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Technical reports.
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Rapports techniques.
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| Added Author |
National Renewable Energy Laboratory (U.S.), issuing body.
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| Standard No. |
1778701 OSTI ID |
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0000-0001-6739-8998 |
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0000-0001-7448-4632 |
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0000-0003-2990-7362 |
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0000-0002-1771-5083 |
| Gpo Item No. |
0430-P-04 (online) |
| Sudoc No. |
E 9.17:NREL/CP-5000-77014 |
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