Related Experiment Video
Updated: Jun 14, 2026

An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
Diffusive and subdiffusive axial transport of granular material in rotating mixers
David Fischer1, Tilo Finger, Frank Angenstein
1Institute of Experimental Physics, Otto-von-Guericke-University, Universitätsplatz 2, D-39106 Magdeburg, Germany.
Abstract:
The segregation of granular mixtures in rotating cylinders into axial bands is not well understood so far. Abnormal diffusion of the grains has been proposed to play an important role in that process. We measure axial diffusion in binary mixtures, completely embedded in water, by means of nuclear magnetic imaging (magnetic resonance imaging). It is found that the small size particles in a radially segregated structure undergo normal (Fickian) axial diffusion, whereas an initial pulse of the large species shows subdiffusive behavior. An interpretation within a model for the particle dynamics is given. The diffusion of small particles occurs in the axial kernel, whereas particles of the large species migrate on the free surface of the granular bed.
Related Concept Videos
Rolling Without Slipping
Irrotational Flow
Steady, Laminar Flow Between Parallel Plates
Centrifugation
Mixing Concrete
The Thermodynamics of Mixing

