Regional numerical modelling of offshore monopile wind turbine impacts on hydrodynamics and sediment transport

Rivier, Aurélie; Bennis, Anne-Claire; Pinon, Grégory; Groß, Markus; Magar, Vanesa

doi:10.1201/b18973-114

Cited by 3 publications

(4 citation statements)

References 14 publications

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“…These visible effects require a point source of turbidity in the flow, rather than a modified velocity field, but do suggest that individual piles can have far reaching effects. Numerical models indicate that there may be small differences in velocity between the wake and the background flow over extensive distances (Rivier et al, 2014), however these differences will be difficult to detect in field or laboratory data over larger differences. The exact size of the wake will clearly depend on the lateral mixing that is present (either in nature or in the models).…”

Section: Discussionmentioning

confidence: 99%

“…Flow velocity has been shown in numerical models to be modified further downstream than is indicated by the size of the scour hole (Rivier et al, 2014;Rivier et al, 2016). Rogan et al (2014) and Rogan et al (2016) give a detailed study of the downstream impacts of turbulence, indicating that pile induced turbulence can remain for up to 80 pile diameters downstream of the pile.…”

Section: Introductionmentioning

confidence: 99%

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Current and wave effects around windfarm monopile foundations

Miles

Martin

Goddard

2017

Coastal Engineering

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Laboratory measurements were undertaken to investigate wave and current velocities in the vicinity of a wind turbine monopile foundation, in order to inform environmental impact assessments and to quantify flow variability in the region of the power take off cable. Flow measurements were made up to 15.5 pile diameters (D) downstream of the pile. Measurements were also taken around the perimeter of the pile (~0.75 D from the pile centre) at the approximate representative height of the power cable. In current-only tests, the mean flow was reduced immediately downstream of the pile, but returned to within 5% of background levels by 8.3 D downstream of the pile centre in representative conditions. A new parameterisation of the velocity recovery is given. The turbulent eddy shedding frequency was well predicted by the Strouhal number. Turbulence peaked at 1.5 D from the pile, and the subsequent decay was parameterised. Velocity magnitudes at the side of the pile were up to 1.35 times greater than background flow rates, in line with potential flow theory. Velocities in the wake region were much less than predicted by potential flow theory, corresponding with increased turbulence. Tests with waves indicated that oscillatory velocities reduced immediately down-wave of the pile, but returned quickly to background levels (by 1.65 to 3.5 D of the pile centre). The general near-pile distribution of the orbital velocity maximum was well represented by potential flow theory. Orbital velocities were reduced immediately up-wave and down-wave of the pile. At the side of the pile in wind sea conditions, the velocity increased up to 1.66 times the background level. This increased to 1.85 times in swell conditions. For orthogonal currents and waves, a velocity parameter was calculated as the mean current plus wave orbital velocity, resolved. With the mean current direction as a reference, the maximum flow was observed at the side of the pile. At 0.75 D from the pile centre, the flow was enhanced by up to 1.2 times the no-pile case. Spectral peaks in the velocity were evident at both wave frequency and at the Strouhal frequency, immediately down current from the pile.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Current and wave effects around windfarm monopile foundations

Miles

Martin

Goddard

2017

Coastal Engineering

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“…The results given by the parameterization are compared with those of the dry cell points method. Previously, Rivier et al (2014) performed simulations on an idealised case which reproduced the semi-diurnal tidal cycle. In the same study, velocity downstream of a monopile simulated with the dry point approach were also compared with experimental measurements.…”

Section: Configurationmentioning

confidence: 99%

Parameterization of wind turbine impacts on hydrodynamics and sediment transport

et al. 2016

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International audienceMonopile foundations of offshore wind turbines modify the hydrodynamics and sediment transport at local and regional scales. The aim of this work is to assess these modifications and to parameterize them in a regional model. In the present study, this is achieved through a regional circulation model, coupled with a sediment transport module, using two approaches. One approach is to explicitly model the monopiles in the mesh as dry cells, and the other is to parameterize them by adding a drag force term to the momentum and turbulence equations. Idealised cases are run using hydrodynamical conditions and sediment grain sizes typical from the area located off Courseulles-sur-Mer (Normandy, France), where an offshore windfarm is under planning, to assess the capacity of the model to reproduce the effect of the monopile on the environment. Then, the model is applied to a real configuration on an area including the future offshore windfarm of Courseulles-sur-Mer. Four monopiles are represented in the model using both approaches, and modifications of the hydrodynamics and sediment transport are assessed over a tidal cycle. In relation Responsible Editor: Bruno Castelle Aurélie Rivier to local hydrodynamic effects, it is observed that currents increase at the side of the monopile and decrease in front of and downstream of the monopile. In relation to sediment transport effect, the results show that resuspension and erosion occur around the monopile in locations where the current speed increases due to the monopile presence, and sediments deposit downstream where the bed shear stress is lower. During the tidal cycle, wakes downstream of the monopile reach the following monopile and modify the velocity magnitude and suspended sediment concentration patterns around the second monopile

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“…In the Ofelia project (Interreg IVa France-England), the M2C was in charge of the numerical modeling for the assessment of the hydro-sedimentary impacts of the monopiles on the future Courseulles s/mer wind farm [21,22]. A subgrid-scale parameterization was developed and implemented in the three-dimensional hydrodynamical model, MARS 3D.…”

Section: Assessment Of the Environmental Impacts Of The Offshore Wind Farm Foundationsmentioning

confidence: 99%

Multi-Disciplinary and Multi-Scale Assessment of Marine Renewable Energy Structure in a Tidal System

Raoux¹,

Robin²,

Pezy³

et al. 2021

JEPT

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The French coast of the Atlantic and English Channel (EC) is promising for the development of Marine Renewable Energy (MRE), including wind, wave, and tidal stream, due to the high velocity of currents in some parts of the area. This paper, focusing on wind and tidal energy, discusses how the implementation of MRE converters influences biodiversity, and vice versa, through biofouling and reef effects. The understanding of these interactions requires the knowledge of the hydro-sedimentary conditions and the macrofauna. The research on these topics, performed at the Continental and Coastal Morphodynamic laboratory (M2C) (UNICAEN, France), is presented through a multi-disciplinary approach by i) studying the hydrodynamic conditions and the macrofauna in Alderney Race, ii) studying the biofouling effects on tidal turbines and their influence on the turbulent wake, iii) assessing the hydro-sedimentary impacts induced by the offshore wind farm, like scouring, and iv) taking an ecosystem approach on MRE, such as the reef effect. From an ecological perspective, the reef effect can be responsible for changes in the structure and function of the ecosystem. Although several studies have analyzed this effect at the species-or community-scale, the propagation of the reef effect at the ecosystem-scale remains unclear. Thus, understanding these ecosystem-scale effects is urgent for future research. From an engineering perspective, biofouling changes the structural characteristics (i.e., supplementary mass) of the converters and thus, affects their performance.

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Regional numerical modelling of offshore monopile wind turbine impacts on hydrodynamics and sediment transport

Abstract: International audienc

Cited by 3 publications

References 14 publications

Current and wave effects around windfarm monopile foundations

Current and wave effects around windfarm monopile foundations

Parameterization of wind turbine impacts on hydrodynamics and sediment transport

Multi-Disciplinary and Multi-Scale Assessment of Marine Renewable Energy Structure in a Tidal System

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