Foreword: a special issue on turbulence and wind energy

To help achieve worldwide goals of reducing the cost of wind energy, the role of turbulence at various relevant length and time scales must be better understood. Turbulence plays important roles in blade performance within a single turbine as well as in interactions among turbines within arrays due to wakes. Other challenges, such as noise, effects of complex topography, variability, uncertainty, stratification, wind resource assessment, and the problem of wind farm underperformance, are all greatly affected by turbulence phenomena. Research synergies that integrate well-controlled experiments, computational fluid dynamics modeling, and theories are required to address such challenges. Such research has seen remarkable growth during the past several years, in various research laboratories around the world. Moreover, wind energy-related special sessions took place in recent years at various international meetings, in particular, at the Summer Meeting of the American Institute of Astronautic and Aeronautics (AIAA) in Honolulu in June 2011 and at the American Physical Society's Division of Fluid Dynamics meeting in Baltimore, in November 2011.