Self-diffusion in inhomogeneous granular shearing flows

Riccardo Artoni (1) , Michele Larcher (2) , James Jenkins (3) , Patrick Richard (1)

1 MAST-GPEM - Granulats et Procédés d'Elaboration des Matériaux
2 Free University of Bozen-Bolzano
3 Cornell University, School of Civil and Environmental Engineering, Ithaca, NY, USA

In this letter, we discuss how flow inhomogeneity affects the self-diffusion behavior in granular flows. Whereas self-diffusion scalings have been well characterized in the past for homogeneous shearing, the effect of shear localization and nonlocality of the flow has not been studied. We therefore present measurements of self-diffusion coefficients in discrete numerical simulations of steady, inhomogeneous, and collisional shearing flows of nearly identical, frictional, and inelastic spheres. We focus on a wide range of dense solid volume fractions, that correspond to geophysical and industrial shearing flows that are dominated by collisional interactions. We compare the measured values first, with a scaling based on shear rate and, then, on a scaling based on the granular temperature. We find that the latter does much better than the former in collapsing the data. The results lay the foundations of diffusion models for inhomogeneous shearing flows, which should be useful in treating problems of mixing and segregation.

Mots clés: 47.57.Gc; 45.70.Mg; 83.50.Ax; 83.80.Fg

Domaines: Autre [cond-mat.other]

Riccardo Artoni, Michele Larcher, James Jenkins, Patrick Richard. Self-diffusion in inhomogeneous granular shearing flows. Physical Review E , 2022, 106 (3), pp.L032901. ⟨10.1103/PhysRevE.106.L032901⟩. ⟨hal-03783250⟩