Segregation of Large and Small Droplets Suspended in Poiseuille Flow

Abstract

In order to investigate the segregation behavior induced by the size difference in suspended particles, we conduct a two-dimensional numerical simulation for suspensions of fluid droplets of two different sizes subjected to a Poiseuille flow between two parallel plates. The large and small droplets are assumed to have equal surface tensions and equal internal viscosities. From the temporal evolutions of the lateral positions of the large and small droplets, it is obtained that the small droplets are displaced closer to the channel walls with increasing fraction of the large droplets whereas the large droplets accumulate more preferentially near the channel centerline with increasing fraction of the small droplets. The probability distribution functions for the droplets indicate that a line of small droplets is formed next to the channel walls at high area fractions, which enhances the size segregation of the droplets.