SIMULATIONS OF SHEAR MIXING OF BIDISPERSE COHESIVE PARTICLES WITH A LARGE SIZE RANGE
LR Aarons, SHOCK COMPRESSION OF CONDENSED MATTER - 2011, PTS 1 AND 2, 1426 (2012).
I have studied the shear mixing of bidisperse collections of cohesive particles in an effort to develop models that would allow one to predict and control the homogeneity of particle composites. The focus has been on the effects of inter-particle cohesion and shear rate on the microstructure of particle composites. As a model problem, the cohesion resulting from the van der Waals force acting between particles is considered. Discrete element method simulations were performed in which initially segregated bidisperse collections of particles featuring a 7: 1 diameter ratio were subjected to plane shear under constant applied stress. Simulations were performed with and without gravity and with a variety of shear rates and particle cohesion strengths for both the large and small particles. The homogeneity of the resultant mixtures was quantified using two order statistics: the spatial variance of the relative concentrations of the different particles and the average size of clusters of small particles. Results indicate that the small particles needed to be sufficiently cohesive for the mixtures to be noticeably more inhomogeneous than mixtures of non-cohesive particles. Without gravity, the particles were most mixed when the big particles were moderately cohesive, while with gravity, mixing worsened as the big particles became more cohesive.
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