Disentangle boundary-layer-depth and pressure-gradient-history effects

Determine separately the contributions of boundary-layer depth, characterized by δ₉₉/D, and upstream pressure-gradient history to the turbulence-intensity response of a wind farm’s adverse-pressure-gradient induction region.

Background

The experiments compare two atmospheric-boundary-layer-like inflows with different depths, but the inflows also differ in their upstream adverse-pressure-gradient histories. Because turbulent boundary layers retain memory of prior pressure-gradient forcing, the stronger turbulence amplification observed for the shallower boundary layer cannot be attributed uniquely to the ratio of boundary-layer depth to rotor diameter.

The unresolved problem is to design measurements or experiments that vary boundary-layer depth and pressure-gradient history independently, allowing the respective effects on farm-induced turbulence amplification to be quantified.

References

Boundary layer depth, \delta_{99}/D, emerges as a candidate key parameter for both the mean and turbulent response, though its role in the turbulence response cannot yet be separated from pressure-gradient history --- disentangling the two is a natural target for future work.

— Wind farm global blockage as an adverse pressure gradient problem: turbulence amplification and spectral modification in the induction region of a model wind farm  (2609.26415 - McGlade et al., 22 Sep 2026) in Section Conclusions