(385e) Characterization of Granular Mixtures by Comparison to Chemical Solution Theory

Our understanding of the behavior of granular materials has benefited from parallels to classical thermodynamics. Granular systems are made up of many small particles, similar to molecular systems which are made of many molecules. This similarity begs for the two types of systems to be analyzed in similar ways. We have found, through the use of particle dynamics simulations, that the behavior of granular mixtures can be classified using an analogy to the thermodynamic theory for chemical solutions. Thermodynamic solution theory provides a connection between bulk solution behavior, the interaction strengths between molecules, and the concentration of each species in the solution. Through our simulations of granular materials, we observe a similar dependence of bulk flow behavior on the inter-particle forces and the composition of the granular mixture. The system we simulated consisted of a binary mixture of granular particles differing only in surface forces (friction or adhesion) rotating in a circular drum. The angle of repose of the mixture was found to depend upon the strength of the inter-particle forces and the composition of the mixture. The interaction between dissimilar particles strongly influences the bulk properties of the material. A granular solution theory may be useful to characterize other bulk properties of non-segregating granular mixtures by either prediction of mixture behavior from particle properties and concentration or estimation of particle interactions from bulk flow behavior.