On the small-scale statistics of Lagrangian turbulence

We provide evidence that the small-scale statistics of the acceleration of a test particle in high-Reynolds number Lagrangian turbulence is correctly described by Tsallis statistics, with entropic index q = 3/2. We present th eoretical arguments why Tsallis statistics can naturally arise in Lagrangia n turbulence and why at the smallest scales q = 3/2 is relevant. A generali zed Heisenberg-Yaglom formula is derived from the nonextensive model. (C) 2 001 Elsevier Science B.V. All rights reserved.