Coherent vorticity dynamics and dissipation in a utility-scale wind turbine wake with uniform inflow. Issue 5 (July 2021)

• Record Type: Journal Article
• Authors: Foti, Daniel
• Is Part Of: Theoretical & applied mechanics letters. Volume 11:Issue 5(2021)
• Publication Date: 2021-07
• Subjects: Wind turbine wake -- Coherent structures -- Vorticity dynamics; Mechanics, Applied -- Periodicals; Mechanics, Analytic -- Periodicals; Mechanics, Analytic; Mechanics, Applied; Periodicals; 620.1
• DOI: 10.1016/j.taml.2021.100292
• Languages: English
• ISSNs: 2095-0349

Abstract

Highlights: Enstrophy is used to identify emergent dynamics in wind turbine wake. Turbulent dissipation and enstrophy are similar except in the near wakes. Coherent enstrophy accounts large portion of total fluctuation in tip vortex. Random enstrophy and strain rate scalar product statistics similar in near wake. Abstract: The vorticity dynamics and its relationship to dissipation in the wake of a utility-scale wind turbine are investigated through large-eddy simulation. The vorticity dynamics is assessed through the enstrophy, which is related to the turbulent dissipation. The averaged enstrophy and turbulent dissipation are shown to be quantitatively similar in the wake. Using temporal phase averaging, the vorticity fluctuations are decomposed into coherent and random fluctuations with respect to the frequency of the tip vortices. The enstrophy in the tip vortices is dominated by coherent fluctuations, while the coherent fluctuations of root vortices are immediately saturated by the random vorticity fluctuations of the unstable hub vortex. The coherent strain rate has significant differences compared to the coherent enstrophy within one diameter downwind of blade tip, but the random enstrophy and strain rate are relatively similar. Differences in coherent enstrophy and strain rate decrease further from the rotor.