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Comparison of Nonlinear Wave-Loading Models on Rigid Cylinders in Regular Waves

Mockutė, Agota; Marino, Enzo; Lugni, Claudio; Borri, Claudio

Authors

Enzo Marino

Claudio Lugni

Claudio Borri



Abstract

Monopiles able to support very large offshore wind turbines are slender structures susceptible to nonlinear resonant phenomena. With the aim to better understand and model the wave-loading on these structures in very steep waves where ringing occurs and the numerical wave-loading models tend to lose validity, this study investigates the distinct influences of nonlinearities in the wave kinematics and in the hydrodynamic loading models. Six wave kinematics from linear to fully nonlinear are modelled in combination with four hydrodynamic loading models from three theories, assessing the effects of both types of nonlinearities and the wave conditions where each type has stronger influence. The main findings include that the nonlinearities in the wave kinematics have stronger influence in the intermediate water depth, while the choice of the hydrodynamic loading model has larger influence in deep water. Moreover, finite-depth FNV theory captures the loading in the widest range of wave and cylinder conditions. The areas of worst prediction by the numerical models were found to be the largest steepness and wave numbers for second harmonic, as well as the vicinity of the wave-breaking limit, especially for the third harmonic. The main cause is the non-monotonic growth of the experimental loading with increasing steepness due to flow separation, which leads to increasing numerical overpredictions since the numerical wave-loading models increase monotonically.

Citation

Mockutė, A., Marino, E., Lugni, C., & Borri, C. (2019). Comparison of Nonlinear Wave-Loading Models on Rigid Cylinders in Regular Waves. Energies, 12(21), 1-22. https://doi.org/10.3390/en12214022

Journal Article Type Article
Acceptance Date Oct 21, 2019
Online Publication Date Oct 23, 2019
Publication Date Oct 23, 2019
Deposit Date Dec 10, 2019
Publicly Available Date Nov 30, -0001
Journal Energies
Print ISSN 1996-1073
Publisher MDPI
Peer Reviewed Peer Reviewed
Volume 12
Issue 21
Article Number 4022
Pages 1-22
DOI https://doi.org/10.3390/en12214022
Keywords offshore wind turbines; monopile; ringing; secondary load cycle; nonlinear waves; hydrodynamic loading models; truncated surface-piercing cylinder; regular waves
Public URL https://hull-repository.worktribe.com/output/3307098
Publisher URL https://www.mdpi.com/1996-1073/12/21/4022

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Publisher Licence URL
https://creativecommons.org/licenses/by/4.0/





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