Analysis of complex wind farm flow over realistic terrain using sparsity-promoting dynamic mode decomposition

Terrain topography affects regions of the atmospheric boundary layer where wind turbines are located. It is widely perceived as advantageous to place wind turbines on the top of a ridge due to the higher energy content in the flow impinging on the turbine. However, the existence of even moderate-altitude topography upstream of the wind farm may give rise to fluctuation dynamics that negatively impact blade loads and energy production. To gain deeper insights into such effects, we apply sparsity-promoting dynamic mode decomposition to the flow field resulting from large-eddy simulation of atmospheric turbulence over a real wind plant's surface topography prescribed by the Shuttle Radar Topography Mission. Our approach allows us to extract the dynamically significant coherent flow structures that impinge on various turbines across the farm and identify terrain-induced flow mechanisms that impact the performance and durability of wind turbines.