| Heterogeneous granular mixtures tend to segregate by size when tumbled in a partially filled, horizontal rotating drum. After a few drum rotations the small grains move towards the axis of rotation and form a buried radial core, which, after several hundred drum rotations, splits into axial bands. This process can display complex, oscillatory wave dynamics during the transient before segregation saturates. In this thesis, we report on measurements of the axial transport of grains in the radial core, the dynamics of the axial segregation process, and the oscillatory wave transient. We show experimentally that two fields, the concentration and dynamic angle of repose, whose coupling was theoretically postulated, do not evolve as predicted, which falsifies a recent model. We also report that the axial transport of small grains in the radial core is subdiffusive. This does not depend on grain type or rotation rate. We show that the self-mixing of monodisperse grains is as well a subdiffusive mixing process. Lastly, we find that the growth rate scaling of the axial segregation pattern increases as a function of drum diameter and grain size ratio. None of these findings are accounted for by any theoretical model of this system. |
