Wind Turbine Wakes and Wind Farms

Modern wind turbines are today clustered in larger and larger wind farms in which the turbines are fully or partially influenced by the wake of upstream located turbines. As a consequence, the wake behind the wind turbines has a lower mean wind speed and an increased turbulence level, as compared to the undisturbed flow outside the farm. Hence, wake interaction results in decreased total production of power, caused by lower kinetic energy in the wind, and an increase in the turbulence intensity. Therefore, understanding the physical nature of the vortices and their dynamics in the wake of a turbine is important for the optimal design of a wind farm. Since many wind farms today also are established in the vicinity of each other, the farm wake is also of great interest.

Modelling the interaction between the atmospheric boundary layer and individual turbines is still a major challenge addressed in this special issue. Validation using experimental techniques is also an important area. Recent advantages in both modelling, using for example machine learning approaches and novel numerical methods, and experimental techniques provides new possibilities to further understanding of the physics of the atmospheric boundary layer, flow inside wind farms, turbine wakes and spiral systems.

This Research Topic covers the various topics related to the aerodynamics and control of wakes and wind farms. In particular the following topics are of special interest:
• Stability and Turbulence,
• Wake Simulations and modelling,
• Wind Farms,
• Wake Interaction,
• Measurements of Wakes,
• Farm wakes,
• Farm control and optimization.