Networks of Broken Links in Granular Flows

Shear zones and reproducible flow fields are key features of granular flows. We experimentally study flows in a split bottom geometry by tracking the motion of all particles in three dimensions. In particular, we investigate how shear zones emerge from individual particle rearrangements, and how the rearrangements transition from reversible to irreversible with increasing strain. In order to analyze rearrangements at the level of particle motion, we define a broken links network, the set of particle pairs that have separated from each other and are no longer in contact. The emergence of a giant component occurs at the same characteristic strain at which a steady shear zone forms. We propose network theory as a new framework to characterize granular flows at the intermediate scale.