Granular dynamics simulations of heap formation:: Effects of feed rate on segregation patterns in binary granular heap

Granular dynamics simulations of a 2D heap formation have been carried out at low- and high-impact feed rates for a 3:1 diameter ratio binary mixture. The data have been analyzed using novel time series and filtering analysis to investigate key representative many-particle dynamic events of the assembly evolution. Spectral analysis of the time series has revealed quite different periodic behavior in the low- and high-impact cases. Segregation occurs in the low-impact case whereas more uniform mixing of the two types of particles arises at high impact, which is consistent with previous experimental observations. The low-impact feed regime is shown to be characterized by discrete surface avalanching manifesting kinetic sieving of the finer particles, in which the large particles move preferentially toward the free surface and segregate in the boundary layer on rolling toward the horizontal base. In contrast, the high-impact feed regime is marked by periodic lateral surging and vertical "pluming" of particles from below toward the free surface.