Relative dispersion in fully developed turbulence

Guido Boffetta
Dipartimento di Fisica Generale, UniversitÓ degli Studi di Torino, Italy

The problem of pair relative dispersion in turbulence is discussed on the basis of recent DNS data (Boffetta and Sokolov, PRL 88, 094501, 2002). Lagrangian statistics is found to be compatible with Richardson description although small systematic deviations are found. The value of the Richardson constant is estimated as C2 = 0.5, in a close agreement with recent experimental findings. By means of exit-time statistics it is shown that the deviations from Richardson's law are a consequence of Eulerian intermittency. The measured Lagrangian scaling exponents are compatible with a set of Eulerian structure function exponents which are remarkably close to standard ones known for fully developed turbulence.