Granular mixing in a Galton board

Abstract

Diffusional mixing of a granular system differs from that of fluids systems in many respects, being the most important, the lack of particulate motion equivalent to molecular diffusion; i.e. there is no relative movement of particles without an energy input.

If we can design a mixer that gives the grains the necessary energy to flow and, at the same time, changes randomly their velocities, we will, in principle, simulate the diffusive movements of molecules in a liquid or gas.

Based on these ideas, we study experimentally the 2D flow of a granular material (discs) through a dispersive medium: a Galton board. It consists on a regular array of obstacles that deflect the discs in random directions so they fall by gravity. In this work we present some preliminary results.