Hydrodynamics of offshore structures with specific focus on wind energy applications

Abstract

This review covers the broad scope of ocean hydrodynamics on offshore marine structures, laying the framework for studying offshore wind energy with a variety of engineering methods. First, water wave theory is described beginning with the fundamental equations of fluid mechanics. A variety of wave theories are discussed, beginning with linearized wave theory, and continuing with Stokes, cnoidal and solitary wave theory. The regions of wave applicability for different theories is shown, summarizing the discussion of water wave theory. Following the introduction of water wave theory, ocean physics are introduced. This section includes ocean wave generation, random waves, spectral representation and commonly used wave spectra, including the Pierson-Moskowitz and JONSWAP spectra. Next, wave-body interaction is presented, first looking at static and then dynamic loads. The dynamic load discussion covers waves, added mass and impulse loads. The section on wave-body interaction concludes with a review of recent literature on wave-body interactions, with emphasis on offshore wind energy. Additionally, a sample of existing engineering tools for modeling hydrodynamics on offshore wind turbines is presented. Finally, finite volume methods are presented to lay the groundwork for reviewing recent computational fluid dynamics research relating to the wave-body interaction problem. The review culminates in a review of recent CFD research.

Variational modelling of wave–structure interactions with an offshore wind-turbine mast

“…The next extension of the model will be to allow for rotational flow to model wave breaking where the free surface can overturn. Non-potential flow and the mixture theory [1,4] of the water-air phase can be used for this purpose. An alternative, which we aim to exploit, is to propose a compressible, Van der Waals-like potential-flow fluid model, that enables the modelling of wave-breaking without actually introducing rotational flow.…”

“…The FSI problems are known to suffer from numerical instabilities [1]. Our method is based on reduction of the whole system to an abstract Hamiltonian form, to which known stable discrete schemes can be applied.…”

“…Both visibility issues and wind supply play major roles in the development of this particular branch of wind energy. There are two main directions of active research in this field, namely offshore floating platforms with wind turbines and fixed-bottom monopile wind farms in shallow water: a review is given in [1]. The first branch is still in the prototype stage of development.…”

Building a Digital Wind Farm

“…The use of vertical axis turbines in an offshore application has been reviewed by Borg et al in a number of papers [ 37 – 39 ], which cover the aerodynamic models used, the methods of mooring the turbines and mathematical models to simulate the combination of wind and wave induced oscillations. In 2015 Benitz et al [ 40 ] covered the hydrodynamics of offshore applications, including water wave theory, ocean physics and how these effect structures such as turbines moored at sea.…”

Wave theory effects on behaviour of a 3D truss offshore structure

“…However, dynamic wave forces have a greater effect on the structure compared to static ones [18]. Benitz et al [19] described the fluid-structure interaction (FSI) analysis of an offshore structure according to the linear and non-linear wave theories. Jia [20] determined the fatigue life of lattice truss type offshore structures by considering wave forces only.…”