Investigating Wind Turbine Impacts on Near-Wake Flow using Profiling Lidar Data and Large-Eddy Simulations with an Actuator Disk Model

Julie Lundquist, Caroline Draxl, Matthew Churchfield, Jeffrey Mirocha, Daniel Rajewski, Nikola Marjanovic, Branko Kosovic

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48 Scopus Citations


Wind turbine impacts on the atmospheric flow are investigated using data from the Crop Wind Energy Experiment (CWEX-11) and large-eddy simulations (LESs) utilizing a generalized actuator disk (GAD) wind turbine model. CWEX-11 employed velocity-azimuth display (VAD) data from two Doppler lidar systems to sample vertical profiles of flow parameters across the rotor depth both upstream and in the wake of an operating 1.5MW wind turbine. Lidar and surface observations obtained during four days of July 2011 are analyzed to characterize the turbine impacts on wind speed and flow variability, and to examine the sensitivity of these changes to atmospheric stability. Significant velocity deficits (VD) are observed at the downstream location during both convective and stable portions of four diurnal cycles, with large, sustained deficits occurring during stable conditions. Variances of the streamwise velocity component, σu, likewise show large increases downstream during both stable and unstable conditions, with stable conditions supporting sustained small increases of σu, while convective conditions featured both larger magnitudes and increased variability, due to the large coherent structures in the background flow. Two representative case studies, one stable and one convective, are simulated using LES with a GAD model at 6m resolution to evaluate the compatibility of the simulation framework with validation using vertically profiling lidar data in the near wake region. Virtual lidars were employed to sample the simulated flow field in a manner consistent with the VAD technique. Simulations reasonably reproduced aggregated wake VD characteristics, albeit with smaller magnitudes than observed, while σu values in the wake are more significantly underestimated. The results illuminate the limitations of using a GAD in combination with coarse model resolution in the simulation of near wake physics, and validation thereof using VAD data.

Original languageAmerican English
Article numberArticle No. 043143
Number of pages21
JournalJournal of Renewable and Sustainable Energy
Issue number4
StatePublished - 1 Jul 2015

Bibliographical note

Publisher Copyright:
© 2015 Author(s).

NREL Publication Number

  • NREL/JA-5000-65157


  • automatic speech recognition systems
  • computer modeling
  • large eddy simulations
  • wind turbines


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