Relative dispersion in fully developed turbulence
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.