Multifractal analysis of turbulent wakes for model wind turbines using large eddy simulation

Over the last years it has become evident that one of the greatest problems during wind turbine operations is related to intermittency between turbulent flow and the blades. An adjacent problem consists in coupling and wake effects of one turbine on its neighbor on extended sites. This research has focused on the detailed study of wind wakes behavior and energy analysis using experiments and fluid simulations of high resolution in both physical and Fourier spaces. Analogously to compressibility and shock interactions rotation and stratification can produce resonant interactions between turbines and lead to damage effects. In this paper numerical results of Large Eddy Simulation in OpenFOAM SOWFA library are presented. Furthermore, scaling of the wake turbulence and wakes interaction with the Neutral Atmospheric Boundary Layer is undertaken via multifractal analysis. Several turbulent indicators, topological aspects and intermittency between a single, two and twelve wind turbines were compared. The study has shown a non-linear growth of intermittency at large scales when several wakes interact with each other. Supplementary findings on spectra and multifractal indicators seem to be extremely useful to optimize wind farms functioning and to increase their performance