Shape-mediated ordering in granular blends.

Many industries mix granular materials of different sizes and shapes. Product quality and consistency are often compromised by demixing of constituent components. Not only is this practically problematic but it is also philosophically unsettling, for on smaller colloidal scales, systems consisting of particles differing by size and shape display quantitatively predictable transitions between mixed and separated phases. We report here that patterns and segregation transitions analogous to those seen in colloidal systems can be found in granular blends differing in shape, concentration, and temperature. This provides insights into the mechanisms of granular segregation.