Dynamical Heterogeneity in Shear-Jammed Granular Systems

Granular suspensions can jam into solids under shear at densities below the isotropic jamming density. At sufficiently large shear stress, these shear-jammed structures undergo plastic flow through small deformations of the particles, contact breaking or slipping, and associated particle rearrangements. Although the shear jamming phenomenon has been extensively studied in recent decades, little is known about how shearjammed states evolve under steady shear. In this work, we report on systematic experiments on the evolution of a shear-jammed system using a recently developed multi-ring Couette shear device. This device imposes a linear shear profile on a layer of photoelastic discs, mimicking a two-dimensional suspension with a small Stokes number. We find that the displacements of the particles exhibit strong spatio-temporal correlations within the range of packing fractions where shear jamming occurs. The particle dynamics are quantified using the fourpoint susceptibility, which grows significantly as the packing fraction approaches the isotropic jamming point from below.

Duke Scholars

Author Joshua Socolar Physics