An important industrial and fundamental problem is the tendency for granular mixtures to
demix or segregate. Small differences in either size or density of the particles lead to flow-
induced segregation. The fundamentals of the process are, in general, imperfectly
understood. Constitutive equations for the case of equal size/different density particle
systems have been proposed; the case of equal density/different size particles is more
complex. We analyze density and size segregation of cohesionless spherical particles in the …

▪ Abstract Granular materials segregate. Small differences in either size or density lead to
flow-induced segregation, a complex phenomenon without parallel in fluids. Modeling of
mixing and segregation processes requires the confluence of several tools, including
continuum and discrete descriptions (particle dynamics, Monte Carlo simulations, cellular
automata computations) and, often, considerable geometrical insight. None of these
viewpoints, however, is wholly satisfactory by itself. Moreover, continuum and discrete …