Wind power is the renewable source with the most successful deployment over the past decade (2007-2016), growing from 93 GW to 490 GW of world-installed capacity during this time (source: “Renewable capacity statistics 2017”, International Renewable Energy Agency). A key role in this spectacular advance has been played by the increased understanding of the turbulent flow in the wind farms, thanks to ever-growing computational power and improved algorithms. In EoCoE-II, the ambition is to be able to simulate a full wind farm over complex terrain with up to 100 wind turbines. Ultimately this will require increases in the size of the problems to be solved and the amount of computational resources of at least two orders of magnitude. The main goal of the wind scientific challenge is to bring the flagship Alya code to Exascale in order to tackle this Large Eddy Simulation (LES) flow problem. Furthermore, the rotating wind turbine blades will be resolved to account for their effect on the flow via a full rotor model. Blade deformation may also be included via the use of sliding meshes. These combined tasks all pose daunting technical challenges for the kernel solvers and meshing algorithms in Alya, for which the EoCoE-II consortium is already well equipped.