## EllipSys3D large eddy simulation data of single wind turbine wakes in neutral atmospheric conditions

2019-11-08T13:42:49Z (GMT)
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This data set represents transient velocity fields obtained by large eddy simulations (LES) of a wind turbine wake, for two different ambient turbulence intensities (4% and 12.8%). EllipSy3D [1-3], the in-house flow solver of DTU Wind Energy, is used to compute the LES data. The complete setup and post processed data are described in:

http://onlinelibrary.wiley.com/doi/10.1002/we.1736/pdf

http://iopscience.iop.org/article/10.1088/1742-6596/1037/7/072001/pdf

The average flow field is published as Cases 5 and 6 in the first article, corresponding to a low and high ambient turbulence intensity. Two additional LES data sets are added (*_NoAD_*.nc), where the wind turbine model is switched off so one can isolate the wake effect.

More specific info:

- The NREL-5MW rotor is modeled as an actuator disk with a fixed force distribution that does not change with time. The force distribution is based on a rotor resolved detached eddy simulation. The rotor diameter D is 126 m.

- The coordinate system is: x=streamwise, y=lateral and z=height.

- The LES data is extracted from a plane at hub height (z=90 m) with:

a) Spatial dimensions x=-1D,8.5D and y=-2D,2D (actuator disk is located at (x,y,z) = (0, 0, 90) m,

b) Spatial sample resolution is D/30 (4.2 m). The numerical grid is twice as fine (D/60).

c) Temporal sample resolution is 0.24 s.

d) Each plane has 286x121 = 34606 spatial points.

e) 15500 planes are stored per case.

- The averaged freestream hub height velocity is close to 8 m/s.

An example Python script, read_netcfd_and_plot.py, is provided which can read and plot the LES data.

http://onlinelibrary.wiley.com/doi/10.1002/we.1736/pdf

http://iopscience.iop.org/article/10.1088/1742-6596/1037/7/072001/pdf

The average flow field is published as Cases 5 and 6 in the first article, corresponding to a low and high ambient turbulence intensity. Two additional LES data sets are added (*_NoAD_*.nc), where the wind turbine model is switched off so one can isolate the wake effect.

More specific info:

- The NREL-5MW rotor is modeled as an actuator disk with a fixed force distribution that does not change with time. The force distribution is based on a rotor resolved detached eddy simulation. The rotor diameter D is 126 m.

- The coordinate system is: x=streamwise, y=lateral and z=height.

- The LES data is extracted from a plane at hub height (z=90 m) with:

a) Spatial dimensions x=-1D,8.5D and y=-2D,2D (actuator disk is located at (x,y,z) = (0, 0, 90) m,

b) Spatial sample resolution is D/30 (4.2 m). The numerical grid is twice as fine (D/60).

c) Temporal sample resolution is 0.24 s.

d) Each plane has 286x121 = 34606 spatial points.

e) 15500 planes are stored per case.

- The averaged freestream hub height velocity is close to 8 m/s.

- Inflow turbulence is modeled by the Mann model.

- Each case corresponds to 1 hour LES. This duration is long enough to get converged mean velocity fields for the low ambient turbulence case. However, the high ambient turbulence case could be improved by running a longer LES because the mean streamwise velocity field in the far wake is still asymmetric, where a symmetric mean streamwise velocity field would be expected.

- The filenames *_UWV_* should have been called *_UVW_*.

An example Python script, read_netcfd_and_plot.py, is provided which can read and plot the LES data.

For questions, please contact: Paul van der Laan, plaa@dtu.dk

EllipSys3D references:

1:
Michelsen, J. A.,

2: Michelsen, J. A., Block structured Multigrid solution of 2D and 3D Elliptic PDEs, AFM 94-06, Department of Fluid Mechanics, Technical University of Denmark, May 1994.

3: Sørensen, N. N.,

*Basis3D - a Platform for Development of Multiblock PDE Solvers*, AFM 92-05, Department of Fluid Mechanics, Technical University of Denmark, December 1994.2: Michelsen, J. A., Block structured Multigrid solution of 2D and 3D Elliptic PDEs, AFM 94-06, Department of Fluid Mechanics, Technical University of Denmark, May 1994.

3: Sørensen, N. N.,

*General Purpose Flow Solver Applied to Flow Over Hills*, Risø-R-827, Risø National Laboratory, Roskilde, Denmark, 1995.