Applicability of different methods for computing wave forces on monopile foundation of offshore wind turbine [應用不同方法計算離岸風機單樁基礎所受波浪力之適用性探討]
Journal
Journal of Taiwan Society of Naval Architects and Marine Engineers
Journal Volume
38
Journal Issue
3-4
Pages
121-134
Date Issued
2020
Author(s)
Abstract
The wave load of an offshore wind turbine foundation is determined by water depth, waves, ocean currents and seabed geology, whether it is a monopile, tripod, jacket, or gravity type foundation. In this paper, different computational methods are used to compute the wave load of the offshore wind turbine monopile foundation. Fifteen wave conditions are set by three periods and five wave heights which gradually increase from small waves to breaking waves, and the force per wave amplitude is defined as a comparison parameter. For the hydrodynamic analysis of the foundation, we use three methods to compute, they are self-developed Morison equation program, potential flow program WAMIT, and the viscous flow RANS software Star-CCM+. Since the physics of viscous flow method is closer to the real physical phenomenon, it is possible to completely simulate linear and nonlinear forces with the method, but it takes a lot of computational time and cost to conduct. In addition to the comparison of the computational results of three methods, the results are also compared with the analytical solutions by MacCamy and Fuchs. The results show that in the case of non-breaking wave, the wave height and force relationship computed by the three methods generally grow linearly, while the force per wave amplitude decreases with the increase of the period, which is consistent with the analytical solutions. However, in the case of breaking waves, the force computed by the RANS method increases sharply, and the force per wave amplitude cannot be accurately observed due to the indeterminate nature of the position of the breaking point. After comparing the results, it is recommended one of the three methods applied for various sea conditions. ? 2019 Taiwan Society of Naval Architects and Marine Engineers. All rights reserved.
Subjects
Foundations
Navier Stokes equations
Ocean currents
Offshore oil well production
Structural loads
Viscous flow
Water waves
Comparison parameters
Computational results
Computational time
Hydrodynamic analysis
Morison equation
Non-breaking waves
Nonlinear force
Physical phenomena
Offshore wind turbines
SDGs
Type
journal article