Richard J.A.M. Stevens

Professor at the University of Twente

Wind energy · Turbulence · Environmental flows

Publication 119 · Wind-farm flow

Evolution and instability of the tip vortices behind a yawed wind turbine

C. Li, A.-K. Gao, L. Liu, X.-Y. Lu, R.J.A.M. Stevens, J. Fluid Mech., 1016, A20 (2025).

Read the article Open-access version (university repository)

Main finding

Yaw produces unequal tip-vortex circulation and asymmetric vortex evolution in the simulated turbine wake. The modal interpretation depends on the numerical model and does not independently establish a yaw-control mechanism.

Vorticity iso-surfaces in the wake of an unyawed and a yawed wind turbine
How to read the figure. Vorticity iso-surfaces behind an NREL 5 MW rotor without yaw and at 30 degrees of yaw, instantaneous (top) and time-averaged (bottom). The tip vortices deform and lose coherence differently once the rotor is yawed, which is the structural change the simulation resolves. The figure shows structure, not mechanism: the modal interpretation built on it is model-dependent and is not independent proof of how yaw control works. Open the full-resolution figure. Figure 6. C. Li et al. (2025). No separate licence is stated here; consult the original publication and credited source before reuse.

Why this matters

Yaw makes neighboring tip vortices evolve asymmetrically through unequal circulation and mutual induction, affecting coherent wake development.

Research context

The study combines lessons from multi-code wake validation, actuator-line resolution, tip-corrected loading, and downstream wake-region mapping. Its high-resolution simulations resolve how yaw deforms and destabilizes tip vortices, while the analytical modal interpretation remains model dependent.

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