This work presents experimental flow measurements of segregating binary mixtures of granular material in a cylindrical tumbler using radioactive particle tracking (RPT). The particles, made of spheronized lactose/avicel with carboxymethyl cellulose binder, have a mean diameter of 200, 400 and 750 microns. The use of RPT enabled the tracking of one radioactive particle flowing with other particles for a long period of time and in a non-intrusive manner. Assuming ergodicity, it was then possible to obtain a complete map of the flow in a cylindrical tumbler mixing system.

The RPT technique used in this work will first be described. The results obtained will next be analyzed. In particular, important characteristics of the flow will be presented, which includes the rate of mixing, the mean velocity profile, the Lyapunov exponents and the entropy. Finally, based on these metrics, the structures of monodisperse and bidisperse particle mixtures will be compared to enlighten some of the important features at the basis of the segregation mechanisms in a cylindrical tumbler.