Numerical and experimental three-dimensional analysis of wakes in complex terrain

This work deals with wind energy exploitation in complex terrain. The topic in general poses several scientific challenges about the comprehension of wind flow on its own and of the interaction of the wind flow with the wind turbines. In particular, in this work the focus is about wake effects in complex terrain. The selected test case is a cluster of four 2.3 MW wind turbines sited in Italy a very complex terrain. Their behavior is analyzed through Supervisory Control And Data Acquisition (SCADA) data mining and the relevant role of the terrain in distorting the wake of the upstream turbines is observed. These experimental evidences stimulate a deeper comprehension through numerical modeling: Computational Fluid Dynamics (CFD) simulations are run, where the presence of the wind turbines is accounted for through the Actuator Disk (AD) model. A novel way of elaborating the output of the simulations is proposed in this work, providing insight into the three-dimensional evolution of the wake proceeding downstream. The main outcome of the numerical analysis is that the terrain distorts the wind flow so that the wake profile is severely asymmetric with respect to the lateral displacement. These results identify the selected test case as an ideal testing ground for further analysis about yawing, mechanical loads and fatigue behavior in complex terrain