Wake meandering in a fully developed experimental scale wind turbine array

It is proposed that large scale atmospheric eddies push the wake of single turbines around. This atmospheric wake interaction, a dynamic shift in the wake over time, is a phenomenon known as wake meandering. Unlike a bluff body shedding frequency, the meandering phenomenon for a turbine is not characterized by a well-pronounced peak in the frequency domain, but rather by a bumb spread over a larger low-frequencies range. Single turbines and an array of 19 rows and 5 columns of turbines were positioned within a simulated atmospheric boundary layer (ABL) in a large boundary layer wind tunnel. High resolution velocity time series was obtained at high enough frequencies to resolve Strouhal number trends behind individual and coalescing wakes of turbines in ABL flow. It is proven that the downstream continuation of the meandering is provided via the intrinsic single wind-turbine ABL coupling behavior. It is proven that this meandering presents itself in large experimental arrays and that far downstream the peak meandering frequency is dominated by the turbine spacing.