Nonaffine motion in flowing highly polydisperse granular media

Abstract: We study the particle-scale motion of highly polydisperse hard disks flowing in a two-dimensional bent channel. We use various size distributions of particles, in which the largest particles are up to five times larger than the smallest. The disks are pushed through an L-shaped channel to drive the particle rearrangements. Although the mean flow is essentially independent of the polydispersity, the motion of individual particles becomes more nonaffine on average for higher polydispersity samples. We characterize the nonaffine motion, finding a qualitative difference in the behavior of small and larger particles: the smaller disks have more nonaffine motion, induced by the larger particles.