scholarly journals Large eddy simulations of the effect of vertical staggering in large wind farms

Wind Energy ◽  
2018 ◽  
Vol 22 (2) ◽  
pp. 189-204 ◽  
Author(s):  
Mengqi Zhang ◽  
Mark G. Arendshorst ◽  
Richard J. A. M. Stevens
Keyword(s):  
Wind Farms ◽  
Large Eddy Simulations ◽  
Large Eddy ◽  
Large Wind

scholarly journals Quantifying variability of Large Eddy Simulations of very large wind farms

2015 ◽  
Vol 625 ◽  
pp. 012027 ◽  
Author(s):  
S J Andersen ◽  
B Witha ◽  
S-P Breton ◽  
J N Sørensen ◽  
R F Mikkelsen ◽  
...  
Keyword(s):  
Wind Farms ◽  
Large Eddy Simulations ◽  
Large Eddy ◽  
Large Wind

scholarly journals Flow visualization using momentum and energy transport tubes and applications to turbulent flow in wind farms

2013 ◽  
Vol 715 ◽  
pp. 335-358 ◽  
Author(s):  
Johan Meyers ◽  
Charles Meneveau
Keyword(s):  
Turbulent Flow ◽  
Flow Visualization ◽  
Energy Transport ◽  
Three Dimensional ◽  
Wind Farms ◽  
Mean Flow ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Using Data ◽  
Large Wind

AbstractAs a generalization of the mass–flux based classical stream tube, the concept of momentum and energy transport tubes is discussed as a flow visualization tool. These transport tubes have the property that no fluxes of momentum or energy exist over their respective tube mantles. As an example application using data from large eddy simulation, such tubes are visualized for the mean-flow structure of turbulent flow in large wind farms, in fully developed wind-turbine-array boundary layers. The three-dimensional organization of energy transport tubes changes considerably when turbine spacings are varied, enabling the visualization of the path taken by the kinetic energy flux that is ultimately available at any given turbine within the array.

scholarly journals Evaluation of the the wind farm wake parametrization with large-eddy simulations of wakes in WRF

2021 ◽  
Author(s):  
Alfredo Peña ◽  
Jeffrey Mirocha
Keyword(s):  
Boundary Layer ◽  
Wind Farm ◽  
Wrf Model ◽  
Wind Farms ◽  
Large Eddy Simulations ◽  
Disk Model ◽  
Mesoscale Models ◽  
Boundary Layer Height ◽  
Wind Speeds ◽  
Large Eddy

<p>Mesoscale models, such as the Weather Research and Forecasting (WRF) model, are now commonly used to predict wind resources, and in recent years their outputs are being used as inputs to wake models for the prediction of the production of wind farms. Also, wind farm parametrizations have been implemented in the mesoscale models but their accuracy to reproduce wind speeds and turbulent kinetic energy fields within and around wind farms is yet unknown. This is partly because they have been evaluated against wind farm power measurements directly and, generally, a lack of high-quality observations of the wind field around large wind farms. Here, we evaluate the in-built wind farm parametrization of the WRF model, the so-called Fitch scheme that works together with the MYNN2 planetary boundary layer (PBL) scheme against large-eddy simulations (LES) of wakes using a generalized actuator disk model, which was also implemented within the same WRF version. After setting both types of simulations as similar as possible so that the inflow conditions are nearly identical, preliminary results show that the velocity deficits can differ up to 50% within the same area (determined by the resolution of the mesoscale run) where the turbine is placed. In contrast, within that same area, the turbine-generated TKE is nearly identical in both simulations. We also prepare an analysis of the sensitivity of the results to the inflow wind conditions, horizontal grid resolution of both the LES and the PBL run, number of turbines within the mesoscale grid cells, surface roughness, inversion strength, and boundary-layer height.</p>

scholarly journals Modeling dynamic wind direction changes in large eddy simulations of wind farms

2021 ◽  
Vol 170 ◽  
pp. 1342-1352
Author(s):  
Anja Stieren ◽  
Srinidhi N. Gadde ◽  
Richard J.A.M. Stevens
Keyword(s):  
Wind Direction ◽  
Wind Farms ◽  
Large Eddy Simulations ◽  
Large Eddy

scholarly journals Wake properties and power output of very large wind farms for different meteorological conditions and turbine spacings: A large-eddy simulation case study for the German Bight

2021 ◽  
Author(s):  
Oliver Maas ◽  
Siegfried Raasch
Keyword(s):  
Boundary Layer ◽  
Power Density ◽  
Boundary Layers ◽  
Power Output ◽  
German Bight ◽  
Wind Farm ◽  
Wind Farms ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Large Wind

Abstract. Germany’s expansion target for offshore wind power capacity of 40 GW by the year 2040 can only be reached if large portions of the Exclusive Economic Zone in the German Bight are equipped with wind farms. Because these wind farm clusters will be much larger than existing wind farms, it is unknown how they affect the boundary layer flow and how much power they will produce. The objective of this large-eddy-simulation study is to investigate the wake properties and the power output of very large potential wind farms in the German Bight for different turbine spacings, stabilities and boundary layer heights. The results show that very large wind farms cause flow effects that small wind farms do not. These effects include, but are not limited to, inversion layer displacement, counterclockwise flow deflection inside the boundary layer and clockwise flow deflection above the boundary layer. Wakes of very large wind farms are longer for shallower boundary layers and smaller turbine spacings, reaching values of more than 100 km. The wake in terms of turbulence intensity is approximately 20 km long, where longer wakes occur for convective boundary layers and shorter wakes for stable boundary layers. Very large wind farms in a shallow, stable boundary layer can excite gravity waves in the overlying free atmosphere, resulting in significant flow blockage. The power output of very large wind farms is higher for thicker boundary layers, because thick boundary layers contain more kinetic energy than thin boundary layers. The power density of the energy input by the geostrophic pressure gradient limits the power output of very large wind farms. Because this power density is very low (approximately 2 W m−2), the installed power density of very large wind farms should be small to achieve a good wind farm efficiency.

scholarly journals A concurrent precursor inflow method for Large Eddy Simulations and applications to finite length wind farms

2014 ◽  
Vol 68 ◽  
pp. 46-50 ◽  
Author(s):  
Richard J.A.M. Stevens ◽  
Jason Graham ◽  
Charles Meneveau
Keyword(s):  
Finite Length ◽  
Wind Farms ◽  
Large Eddy Simulations ◽  
Large Eddy

scholarly journals Turbulence and entrainment length scales in large wind farms

2017 ◽  
Vol 375 (2091) ◽  
pp. 20160107 ◽  
Author(s):  
Søren J. Andersen ◽  
Jens N. Sørensen ◽  
Robert F. Mikkelsen
Keyword(s):  
Wind Farm ◽  
Wind Farms ◽  
Turbulent Structures ◽  
Length Scales ◽  
Self Organized ◽  
Reference Simulation ◽  
Large Eddy ◽  
Entrainment Process ◽  
Proper Orthogonal ◽  
Large Wind

A number of large wind farms are modelled using large eddy simulations to elucidate the entrainment process. A reference simulation without turbines and three farm simulations with different degrees of imposed atmospheric turbulence are presented. The entrainment process is assessed using proper orthogonal decomposition, which is employed to detect the largest and most energetic coherent turbulent structures. The dominant length scales responsible for the entrainment process are shown to grow further into the wind farm, but to be limited in extent by the streamwise turbine spacing, which could be taken into account when developing farm layouts. The self-organized motion or large coherent structures also yield high correlations between the power productions of consecutive turbines, which can be exploited through dynamic farm control. This article is part of the themed issue ‘Wind energy in complex terrains’.

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