(205d) Controlling Mixing and Segration in Fine Particle Systems

The primary hindrance to good particle mixing lies in the fact that particles that differ even slightly in size, density, etc. easily segregate, and little is known regarding limiting this unmixing tendency. Recent work in our lab on L-systems -- particle systems that are cohesive due to the presence of liquid bridges -- has shown that substantial control of the mixing and segregation tendencies of a wet granular system may be obtained via manipulation of the cohesive interaction. A simple model of asymptotic mixing behavior allows us to analytically determine phase diagrams of mixed and segregated "phases". From a practical standpoint, control of this behavior is then simply obtained through changes of the interstitial (liquid-bridge) fluid. For dry fine particle systems, however, this this problem becomes more complex. The interparticle cohesive force, here due to van der Waals attraction (which we will call V-systems), can be altered only through changes in particle composition. In this paper, we examine methods aimed at addressing the control of mixing and segregation of fine particles, i.e., V-systems. Computational results of V-systems will be used to test a modified version of our asymptotic mixing theory -- now made applicable to V-systems -- and alternative methods of control will be explored.