Competition between chaos and order: Mixing and segregation in a spherical tumbler

J. F. Gilchrist, J. M. Ottino
2003 Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics  
We investigate the competition between granular mixing and segregation in a sphere rotating and rocking on two orthogonal axes. Operation corresponds to the continuous-flow regime and the flow within the sphere is three-dimensional and time-periodic. Experimental results are organized in a frequency/amplitude phase diagram showing modes of segregation ͑band formation/no axial bands͒; segregated bands are remarkably robust and survive rocking amplitudes as large as 60 degrees over a wide range
more » ... frequencies. Details differ, but the phenomenon occurs under both dry and slurry conditions, that is, when all air is replaced by a liquid. Experimental space-time plots of the stationary segregated patterns agree well with Poincaré maps obtained using a continuum model of the flow, suggesting that the final segregation patterns are relatively independent of materials tumbled.
doi:10.1103/physreve.68.061303 pmid:14754197 fatcat:nlmtail2u5etxknpmdygqzwthq