On the scaling properties of 2d randomly stirred Navier–Stokes equation

by Dr Paolo Muratore-Ginanneschi (University of Helsinki)

Wednesday 7 May 2008, 10:00 → 11:00 Europe/Stockholm

Nordita seminar room

We inquire the scaling properties of the 2d Navier-Stokes equation sustained by a forcing field with Gaussian statistics, white-noise in time and with power-law correlation in momentum space of degree 2-2*epsilon. This is at variance with the setting usually assumed to derive Kraichan's classical theory. We contrast accurate numerical experiments with the different predictions provided for the small epsilon regime by Kraichnan's double cascade theory and by renormalization group (RG) analysis. We give clear evidence that for all epsilon Kraichnan's theory is consistent with the observed phenomenology. Our results call for a revision in the RG analysis of (2d) fully developed turbulence.