Saarblitz, Wind farm in HDR, flickr.com, creative commons by-nc-sa 2.0

VestasFOAM

Since late 2009, Vestas has switched focus from commercial CFD packages to in-house CFD development using the OpenFOAM CFD toolkit [1]. This has resulted in the VestasFOAM process which is currently deployed globally within the company and used in thousands of micro-siting wind resource assessment projects to date.

Latest version

VestasFOAM 1.1.0 - LES/DES

Submitted by Yavor Hristov on May 5, 2015 - 12:00am
Main hypothesis

VestasFOAM 1.1.0 - DES is built upon the pimpleFoam solver packaged within the publically available OpenFOAM distribution [1]. The k-omega SST DES [2] turbulence model has been implemented in-house. If desired buoyancy can be selected through the Boussinesq approximation.

VestasFOAM - DES is used operationally to determine probability density functions of wind veer and wind shear and compliance with IEC standards for class A,B and C sites. This has been done with good success both forensically (i.e. once problems have been detected on old sites) and during the initial micro-siting activities when transient flow suspicions are raised on prospective sites.

VestasFOAM 1.1.0 - LES is built upon the SOWFA project led by NREL [3]. The SOWFA code has been modularized to fit within the VestasFOAM automated CFD workflows and linked to Vestas turbine libraries for efficient/automated case setup, execution and post-processing. Currently this is only valid on flat terrain/offshore.

For both LES/DES, grids are automatically generated in Pointwise [4] using a structured hyperbolic extrusion. Great care is taken to control grid quality, with small expansion ratios from terrain to rotor bottom, and uniform grid spacing through the turbine/wake areas. As with our steady process, when sufficiently vertically distanced from turbines, the horizontal mesh resolution is continually reduced in order to lower mesh size.

Software
Solver
OpenFOAM
License
Regime
Turbulence
Turbulence closure
Turbulence model

standard Smagorinsky (LES) / k-Omega SST (DES)

Atmospheric boundary layer
Range
Coriolis
Yes
Atmospheric Stability
Atmospheric Stability
Yes
Stability model
Boussinesq approximation
Canopy
Forest canopy
No
Wind farm
Wind turbine
Yes
Rotor model
Wake model
Wind farm range
Additional information

Although possible to activate the DES model with the actuator line method, this has not yet been investigated with VestasFOAM.

References

[1] OpenFOAM CFD Toolkit - www.openfoam.com

[2] F. R. Menter, M. Kuntz, R. Langtry, "Ten Years of Industrial Experience with the SST Turbulence Model", Turbulence, Heat and Mass Transfer 4, 2003.

[3] Matthew J. Churchfield, Sang Lee, John Michalakes, Patrick J. Moriarty, "A numerical study of the effects of atmospheric and wake turbulence on wind turbine dynamics," Journal of TurbulenceVol. 132012.

[4] Pointwise Inc. -  www.pointwise.com

Content Visibility

Public