Impact of atmospheric stability on wake interactions and power performance of offshore wind farm clusters

The rapid expansion of offshore wind energy involves deploying large wind farms in clusters, creating complex aerodynamic interference that affects energy production. However, the comprehensive impact of atmospheric stability on the performance of these clusters is not yet fully understood, which hinders the optimisation of their layout and energy yield. This study tests the central hypothesis that a downstream farm induces a measurable blockage effect on an upstream farm, and that the magnitude of this ’group clustering effect’ is fundamentally modulated by atmospheric stability. High-fidelity large-eddy simulations of single and dual NREL 5 MW wind farm configurations were performed under unstable, neutral, and stable atmospheric conditions to investigate this phenomenon. Results reveal that, compared to neutral conditions, unstable atmospheres increased the power of the upstream and downstream farms by 33.98 % and 15.43 % respectively, whereas stable conditions led to power reductions of 19.21 % and 19.09 %. These findings confirm that atmospheric stability is a critical determinant of inter-farm wake dynamics, and crucially, that the beneficial characteristics of an unstable atmosphere are themselves altered by the first farm, leading to a diminished relative power gain for the subsequent farm and providing vital insights for the design of next-generation wind farm clusters.