Segregation-driven organization in chaotic granular flows

An important industrial problem that provides fascinating puzzles in patter n formation is the tendency for granular mixtures to de-mix or segregate. S mall differences in either size or density lead to flow-induced segregation . Similar to fluids, noncohesive granular materials can display chaotic adv ection; when this happens chaos and segregation compete with each other, gi ving rise to a wealth of experimental outcomes. Segregated structures, obta ined experimentally, display organization in the presence of disorder and a re captured by a continuum flow model incorporating collisional diffusion a nd density-driven segregation. Under certain conditions, structures never s ettle into a steady shape. This may be the simplest experimental example of a system displaying competition between chaos and order.