The wake behind a wind turbine in the Atmospheric Boundary Layer (ABL) is investigated using a numerical simulation method. From the view of cost effectiveness, collective installation (wind farm) is desired because it can save the total length of the power transmission lines and the labor cost for maintenance. However, the wake from the upwind wind turbine may significantly reduces the power production of the downstream wind turbine and cause large load variations on the blades. Numerical methods based on Computational Fluid Dynamics (CFD) are efficient to investigate the structures and characteristics of the wind turbine wakes. In this study, the relationship between the velocity profile of the ABL and the wake vortex breakdown is discussed. It is found that the vortex breakdown occurs faster in the ABL flow conditions.
