Title: Mixing, Segregation, and Chaos in Granular Materials
Speaker: Professor Julio Ottino
Speaker Info: Northwestern U.
Simultaneous mixing and segregation of granular materials is of considerable practical importance; the interplay among both process is however, poorly understood from a fundamental viewpoint. A significant complicating factor, particularly in contrast with the mixing of fluids, is the tendency for materials to segregate or demix as a result of differences in the properties of the materials being mixed. This work reviews experimental, theoretical, and computational work in mixing and segregation of powders. Attention is placed primarily on non-cohesive powders undergoing segregation due to density differences in quasi 2D containers operating in the continuous flow regime. We review continuum descriptions of segregation and compare the models with results obtained from particle dynamics and Monte Carlo simulations. A particularly noteworthy development is the possibility of generating chaotic advection in noncircular containers. A practical consequence of this finding is that it opens avenues for the improvement of many existing industrial processes and also allows for the kind of progress in the descriptions of mixing of granular materials that we have seen in the fluid mixing since the connection with chaos was brought up several years agoDate: Friday, February 20, 1998