Simulated wave hydrodynamics and loading on an offshore monopile

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dc.contributor.advisor Kelliher, Denis en
dc.contributor.advisor Thomas, Gareth en
dc.contributor.advisor Borthwick, Alistair en Edesess, Ariel J. 2018-10-12T10:35:47Z 2018-10-12T10:35:47Z 2018 2018
dc.identifier.citation Edesess, A. J. 2018. Simulated wave hydrodynamics and loading on an offshore monopile. PhD Thesis, University College Cork. en
dc.identifier.endpage 171 en
dc.description.abstract Maintenance costs of offshore wind power, where fixed monopile support columns make up the majority of wind turbine types, are up to three times higher than those associated with onshore wind power. High costs are exacerbated by difficulties accessing the turbines in their marine environment. Safe transfer by crew transfer vessel (CTV) requires prediction of vessel motion whilst in contact with the turbine monopile. Future vessel motion prediction first requires analysis through analytical and numerical methods of the local hydrodynamic wave field and wave loading on the monpile turbine in ocean waves. A location-dependent unidirectional sea state is represented by superposition of periodic waves with amplitude components an, obtained from the spectral distribution of free surface displacement data from a single wave buoy located at the Teesside Offshore Wind Farm in the southern North Sea. Wave buoy data was obtained for each season during the 2015/2016 time period, providing a record of seasonal changes that occur in the spectral distribution. Wave loading in the local irregular sea state was predicted using the Morison equation and the linear diffraction formulation. Numerical predictions were obtained using OpenFOAM and a modification of the multiphase interFoam solver for generating free surface waves, where a boundary condition for inputting irregular waves based on the local wave spectra was developed for the purpose of this thesis. For unimodal spectral distributions, which occur in 50% of the data sets with a third data set displaying a small secondary peak, the analytical solutions for the diffracted hydrodynamics and wave loading show satisfactory agreement with the numerical predictions, provided a slip boundary condition is applied on the cylinder. Comparisons were made between analytical solutions and numerical predictions for each of the four data sets, where the irregular wave field was simulated first in a numerical wave tank and then interacting with a fixed cylinder representative of a monopile wind turbine. Simulations were run using both a slip and non-slip cylinder wall boundary conditions in order to determine the effects of viscosity. OpenFOAM can potentially provide better predictions of the diffracted water particle kinematics resulting from the interaction between the sea state at Teesside Offshore Wind Farm and the turbine monopiles, but with a significantly increased computational overhead. The analytical solutions provide satisfactory and relatively fast solutions, although at the expense of neglecting higher-order terms. Both methods presented in this thesis provide practitioners with enhanced knowledge of the seasonspecific local hydrodynamics and wave loading based on actual sea state data, rather than relying on a parametric location-specific representation. Enhanced knowledge of the hydrodynamic field affecting vessel motion will give a better prediction of vessel motion under operating conditions, and eventual determination of the limiting conditions under which the vessel will remain steady. en
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher University College Cork en
dc.rights © 2018, Ariel J. Edesess. en
dc.rights.uri en
dc.subject O&M en
dc.subject OpenFOAM en
dc.subject Offshore wind en
dc.subject Applied mathematics en
dc.subject Wave loading en
dc.subject Hydrodynamic en
dc.title Simulated wave hydrodynamics and loading on an offshore monopile en
dc.type Doctoral thesis en
dc.type.qualificationlevel Doctoral en
dc.type.qualificationname PhD en
dc.internal.availability Full text available en Not applicable en
dc.description.version Accepted Version
dc.contributor.funder Science Foundation Ireland en
dc.description.status Not peer reviewed en Civil and Environmental Engineering en
dc.check.type No Embargo Required
dc.check.reason Not applicable en
dc.check.opt-out Not applicable en
dc.thesis.opt-out false
dc.check.embargoformat Embargo not applicable (If you have not submitted an e-thesis or do not want to request an embargo) en
dc.internal.conferring Autumn 2018 en
dc.internal.ricu Centre for Marine Renewable Energy Ireland (MaREI) en
dc.relation.project info:eu-repo/grantAgreement/SFI/SFI Research Centres/12/RC/2302/IE/Marine Renewable Energy Ireland (MaREI) - The SFI Centre for Marine Renewable Energy Research/ en

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© 2018, Ariel J. Edesess. Except where otherwise noted, this item's license is described as © 2018, Ariel J. Edesess.
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