Spatio-temporal koopman decomposition in offshore wind turbines

This article presents the spatio-temporal analysis of the flow structures in the wake of an offshore wind turbine using spatio-temporal Koopman decomposition (STKD). STKD is a new method that obtains and combines the main frequencies and wavenumbers (characterizing a specific spatial direction) contained in a flow, with the aim at representing the main flow structures as a whole of traveling waves. The results obtained show that the complex behaviour of the wake of the wind turbine is mainly driven by a single traveling wave moving downstream and a combination of small amplitude traveling waves, related to velocity fluctuations, that represent the flow rotation.