An experimental study on the stability of interacting piles formed from grains with different sizes

Abstract

We investigate the pattern formation resulting from the interaction of quasi-two dimensional granular piles. The setup is comprised of mono-dispersed spheres drop into adjacent pipes where one pipe supplies larger spheres than the other. As the distance between the pipes decreases, the two piles merge to form one pile increasing the degree of granular. Using two sizes of sago as our spherical grains, we have observed experimentally that the resulting pile for the bigger spheres becomes more stable, while the piles for smaller spheres becomes less stable as a result of the interaction. The degree of stability is quantified based on repose angle variations. We also report a couple of interesting results that we believe might trigger some modeling interest in a system of this type, namely, (1) stability is improved by setting an impact absorber at the base of the setup and (2) kinks and logarithmic tails are observed in the evolved heap.