Chaotic mixing of granular material in slowly rotating containers as a discrete mapping

Chaotic mixing of granular material in a two-dimensional slowly rotating no ncircular container in the absence of granular diffusivity is studied analy tically and numerically as a discrete mapping. The noncircularity of a drum produces a time periodic disturbance and chaotization of the flow field. T he location of the fixed points of the mapping and the separatrices of the hyperbolic points are determined in a closed analytical form. (C) 1999 Amer ican Institute of Physics. [S1054-1500(99)00604-7].