Accepted Talks Proceedings »

EFFECTIVE DIFFUSION AND DISPERSION OF INERTIAL PARTICLES IN FLOWING FLUIDS

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We perform an analytical study of the inertial-particle dynamics in the limit of small but finite inertia, in incompressible flows, exploring two specific issues. First, by means of a multiscale expansion, we analyse the particle effective diffusivity, and in particular its dependence on Brownian diffusivity, gravity and particle-to-fluid density ratio. We identify some cases of anomalous diffusion. Secondly, we investigate the concentration of particles continuously emitted from a point source with a given exit velocity distribution. The anisotropy of the latter turns out to be a necessary factor for the presence of a correction (with respect to the corresponding tracer case) at order square root of the Stokes number. In both cases, we obtain forced advection–diffusion equations for auxiliary quantities in the physical space, thus simplifying the problem from the full phase space to a system which can easily be solved numerically.

Author(s):

Marco Martins Afonso    
I3M - Université Montpellier 2
France

Andrea Mazzino    
DICCA - Università di Genova, CNISM & INFN
Italy

Paolo Muratore-Ginanneschi    
DMS - University of Helsinki
Finland