Implications of Shear and Thermal Stratification on Wind Turbine Tip-Vortex Stability

Amy Hodgkin, Sylvain Laizet, Georgios Deskos

Research output: Contribution to conferencePaperpeer-review


The interaction between wind turbines in a wind farm through their wakes is a phenomenon that has been studied for decades and is still relevant today. Turbines clustered together in arrays will often operate in the wake of other upstream turbines which may lead to significant power losses and fatigue loads. For modern large-scale wind turbines, the mean shear velocity profile and thermal stratification are major components of the atmospheric boundary layer so it is important to understand their impact on near-wake development. Additionally, veer is present due to the rotation of the Earth. The impact of shear, thermal stratification and veer on the stable wake length of turbines with a dynamic control strategy is studied numerically in this work using a suite of highly resolved large-eddy simulations. Instantaneous flow fields are extracted from the simulations and used to conduct proper orthogonal decomposition (POD) and compute the mean kinetic energy fluxes by different POD modes to better understand the tip-vortex instability mechanisms. Our findings show that the dynamic pitch control scheme is able to shorten the stable wake length to about 1.5R in uniform flow. Shear can significantly affect the break up of wind turbine tip-vortices as well as the shape and stable length of the wake, whereas thermal stratification seems to only have limited contribution to the spatial development of the near-wake field. Veer causes the wake boundary to skew but has a limited impact on the wake length.

Original languageAmerican English
Number of pages6
StatePublished - 2022
Event12th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2022 - Osaka, Virtual, Japan
Duration: 19 Jul 202222 Jul 2022


Conference12th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2022
CityOsaka, Virtual

Bibliographical note

Proceedings available online:; See NREL/JA-5000-82017 for related paper published in Wind Energy

NREL Publication Number

  • NREL/CP-5000-85159


  • length thermal stratification
  • near-wake field
  • shear
  • stable wake
  • tip-vortex stability


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