Effects of atmospheric stability on the performance of a wind turbine located behind a three-dimensional hill

Liu, L.; Stevens, R.J.A.M.

doi:10.1016/j.renene.2021.05.035

Publication 83 · Atmospheric turbulence

Effects of atmospheric stability on the performance of a wind turbine located behind a three-dimensional hill

L. Liu, R.J.A.M. Stevens, Renewable Energy 175, 926-935 (2021).

Main finding

The study asks how stable, neutral, and convective atmospheric states change the power, aerodynamic-force variability, and wake of one NREL 5-MW turbine placed 6D behind a three-dimensional hill. Boussinesq LES uses a Lagrangian scale-dependent SGS model, immersed boundary terrain, and an actuator-line turbine (D=126 m) at fixed 9.1552 rpm; tower, nacelle, and controller dynamics are omitted. The cosine-squared hill has height h=90 m=z_h and half-length l=2.5h.

Velocity deficit and turbulence intensity behind a three-dimensional hill under three atmospheric stabilities — **How to read the figure.** Time-averaged velocity-magnitude deficit (left) and turbulence intensity (right) for flow over a three-dimensional hill in stable, neutral and convective conditions. The hill wake changes shape and vertical position with stability, which is what carries the turbine 6D downstream into or out of it. Figure 6 gives the power that results. Open the full-resolution figure. Figure 4. L. Liu and R.J.A.M. Stevens (2021). No separate licence is stated here; consult the original publication and credited source before reuse.

Why this matters

The clearest lesson is that veer can move a turbine into or out of a hill wake.

Research context

The three atmospheric states combine wake displacement by veer, hill-wake deficit, low-level-jet or high-momentum entrainment, and terrain-generated turbulence. They do not isolate atmospheric stability as a single causal variable.

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