The fractal turbulent/non-turbulent interface in the atmosphere

Abstract. With their steady growth in size, wind turbines are reaching unprecedented heights. As a result, at these heights they are affected by wind conditions that have not yet been investigated in detail. With increasing heights, a transition to laminar conditions becomes more likely. In this paper, the presence of the turbulent/non-turbulent interface (TNTI) in the atmosphere is studied. Three different sites are investigated. Our fractal scaling analysis leads to typical values known from ideal laboratory and numerical investigations. The height distribution of the probability of the TNTI is determined and shows a frequent occurrence at the height of the rotor of future multi megawatt turbines. The indicated universality of the fractality of the TNTI allows the use of simplified models in laboratory and numerical investigations.