Richard J.A.M. Stevens

Physics of Fluids

University of Twente

Publication 57 · Wind-farm flow

When actuator-line detail changes the wind-turbine wake

R.J.A.M. Stevens, L.A. Martínez-Tossas, and C. Meneveau, Renewable Energy 116, 470–478 (2018).

Listed by Web of Science in the top 1% of papers compared with contemporaries. The article and figure are open access under CC BY 4.0.

Main finding

The actuator-line model reproduces the near-wake velocity and turbulence profiles better through approximately three rotor diameters. Farther downstream, the mean profiles predicted by the actuator-line and actuator-disk models become increasingly similar. Including nacelle and tower forces further improves the local near-wake prediction.

Measured and simulated mean velocity and turbulence-intensity profiles downstream of a model wind turbine
How to read the figure. The upper panels show normalized mean streamwise velocity and the lower panels show normalized streamwise turbulence intensity, from one rotor diameter upstream to twenty diameters downstream. Circles are wind-tunnel measurements; green and red curves are actuator-line and actuator-disk simulations. Dashed curves include nacelle and tower forces. The largest model differences occur in the sampled near wake, while the mean profiles become increasingly similar downstream. Open the full-resolution figure. Figure 4, cropped. R.J.A.M. Stevens, L.A. Martínez-Tossas, and C. Meneveau (2018), CC BY 4.0.

Why this matters

Turbine-model fidelity is distance dependent. In this comparison, the actuator-line representation and explicit nacelle and tower forces matter most for local near-wake profiles. Farther downstream, the mean velocity profiles from the actuator-line and actuator-disk models approach each other. The result supports choosing turbine-model detail for the quantity and wake distance of interest rather than assuming one representation is uniformly superior.

Research context

The comparison uses coarse-grid large-eddy simulations and measurements for a model turbine in a neutral wind-tunnel boundary layer. It considers both a single turbine and an aligned 10-row farm with three periodic columns. The study evaluates velocity and turbulence profiles, not wind-farm power, and the model-scale nacelle and tower are relatively large compared with a field-scale turbine. The result therefore establishes a distance- and metric-specific fidelity boundary, not a general ranking of actuator models.

Underlying data: 4TU.ResearchData DOI 10.4121/21375657 contains the experimental and simulation data and corresponding Python scripts for Figures 4, 6, and 7.

Read the article Open-access version View in the complete publication list Related wind-farm LES research