Atmospheric stability effects on farm-to-farm wake interactions: A large-eddy simulation study

This study uses large-eddy simulations to examine how atmospheric stability and inter-farm spacing jointly influence wind–farm interactions. The results demonstrate that farm-to-farm interactions are governed by the coupled action of turbulence-mediated wake recovery and gravity-wave-mediated large-scale atmospheric adjustment, whose relative importance varies with stability. Under stable conditions, reduced ambient mixing promotes highly persistent farm wakes, with velocity deficits extending beyond 15 km and first-row power losses of up to 40% in the downstream farm. In contrast, convective conditions accelerate wake recovery, although inter-farm influence remains measurable due to stratification in the free atmosphere. In all cases, the turbulence generated by the upstream farm accelerates the recovery of the wake from the downstream farm, with the strongest relative impact under stable, low-turbulence conditions. Despite large inflow velocity deficits, the turbulence intensity within the downstream farm rapidly adjusts to levels comparable to those within the upstream farm, suggesting that turbine-generated mixing largely governs in-farm turbulence. In strongly stratified cases, this turbulence-driven interaction is further coupled with gravity-wave-like vertical flow adjustments that modulate blockage and wake evolution. As a result, power output reflects the combined effects of turbulence history, stratification, and wave-induced pressure adjustment, with blockage effects ranging from ∼18% in stable conditions to ∼4% in conventionally neutral cases. The cumulative presence of two wind farms also alters the boundary-layer structure, promoting internal boundary-layer-like adjustments, Coriolis-induced asymmetries, and stability-dependent changes in turbulent momentum transport.