Clustering-induced attraction in granular mixtures of rods and spheres

Abstract

Depletion-induced aggregation of rods enhanced by clustering is observed to produce a novel model of attractive pairs of rods separated by a line of spheres in a quasi-2D, vertically-shaken, granular gas of rods and spheres. We show that the stability of these peculiar granular aggregates increases as a function of shaking intensity. Velocity distributions of spheres inside and outside of a pair of rods trapping a line of spheres show a clear suppression of the momentum acquired by the trapped spheres. The condensed phase formed between the rods is caused by a clustering instability of the trapped spheres, enhanced by a vertical guidance produced by the confining rods. The liberated area corresponding to direct excluded-volume pairs and indirect depletion-aggregated pairs is measured as a function of time. The stability of rod pairs mediated by spheres reveals an attraction comparable in strength to the one purely induced by depletion forces.

9 pages, 6 figures

References in corpus (2)

• Clustering, Order, and Collapse in a Driven Granular Monolayer
• Tunable long range forces mediated by self-propelled colloidal hard spheres

Cited by in corpus (4)

• Demixing and tetratic ordering in some binary mixtures of hard superellipses
• Small-scale demixing in confluent biological tissues
• Depletion Forces in Athermally Sheared Mixtures of Frictionless Disks and Rods in Two Dimensions
• Ballistic propagation of density correlations and excess wall forces in quenched granular media