Global reliance on wind energy continues to grow, leading to an increasing number of wind farms implemented in complex topographies. However, there remains a significant research gap on how the terrain’s features affect the wake recovery, especially when the irregularities scale with the wind turbine’s size. This study uses field data and Reynolds-averaged simulations to quantify the influence of topographical features on a wind farm’s wake recovery and power generation. To characterize the terrain surrounding the turbines, this study introduces two parameters—the Downwind Slope and the surface complexity length ζ—which quantify the local average terrain unevenness. The findings demonstrate that turbines in terrains with streamwise positive slopes exhibit faster wake recovery, averaging 6.35D in length (D = turbine diameter), followed by complex-flat terrain (8.7D on average), then descending terrains with the least beneficial wake recovery (9.2D on average). A terrain with a higher surface complexity also improves wake recovery owing to the turbulent entrainment that enhances momentum transport exchange into the wake. Additionally, simulations of the same turbine distribution, but in a completely flat terrain, showed that the complex terrain may lead to lower performance compared to the idealized flat terrain: 11.5% of power generation decrease in our case. The latter highlights the importance of considering topographic effects when planning wind energy projects.
Torrejón-Fontana et al. (Mon,) studied this question.