2006/10/25 by A. Bistagnino, Bistagnino, A., G. Boffetta +3
Physics and Astronomy · #Chaotic Dynamics (nlin.CD) #FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn) #nlin.CD #physics.flu-dyn
paper · pdf · doi:10.48550/arxiv.nlin/0610060
4 pages, 5 figures
arxiv created 2006/10/25 · arxiv updated 2009/12/01
Single-particle dispersion in the Bolgiano--Obukhov regime of two-dimensional turbulent convection is investigated. Unlike dispersion in a flow displaying the classical K41 phenomenology, here, the leading contribution to the Lagrangian velocity fluctuations is given by the largest eddies. This implies a linear behavior in time for a typical velocity fluctuation in the time interval t. The contribution to the Lagrangian velocity fluctuations of local eddies (i.e. with a characteristic time of order t), whose space/time scalings are ruled by the Bolgiano--Obukhov theory, is thus not detectable by standard Lagrangian statistical observables. To disentangle contributions arising from the large eddies from those of local eddies, a strategy based on exit-time statistics has successfully been exploited. Lagrangian velocity increments in Bolgiano convection thus provide a physically relevant example of signal with more than smooth fluctuations.