A review on two methods to detect spatio-temporal patterns in wind turbines

This Chapter presents a review on two methods for the analysis of flow structures in wind turbines. These methods are higher order dynamic mode decomposition and spatio-temporal Koopman decomposition, which are highly efficient tools suitable for the detection of spatio-temporal patterns in complex flows. These two techniques have been applied to detect the main flow structures in a cross-flow wind turbine in turbulent regime, and in an horizontal wind turbine, which is laminar in the near field but transitioning to turbulence in the far field. Using these methods, a reduced number of traveling waves which are responsible for triggering the flow transition, are able to describe the aforementioned complex flows.