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 asse mbly evolution. Spectral analysis of the time series has revealed quite dif ferent periodic behavior in the low- and high-impact cases. Segregation occ urs in the low-impact case whereas more uniform mixing of the two types of particles arises at high impact, which is consistent with previous experime ntal observations. The low-impact feed regime is shown to be characterized by discrete surface avalanching manifesting kinetic sieving of the finer pa rticles, in which the large particles move preferentially toward the free s urface and segregate in the boundary layer on rolling toward the horizontal base. In contrast, the high-impact feed regime is marked by periodic later al surging and vertical "pluming" of particles from below toward the free s urface.