Microscopic Rearrangements in the Flow of Highly Polydisperse Dense Emulsions

We study the flow of dense polydisperse quasi-two-dimensional emulsions. In particular, we are interested in highly polydisperse samples with the largest droplets as much as ten times the size of the smallest. The droplets are confined between two parallel glass plates so that the system is quasi-2D and driven by a syringe pump. We use video microscopy to examine local rearrangements as the sample flows and we study how rearrangements differ for large and small droplets. In particular, we find the large droplets generally follow the mean flow, while the small droplets have significant nonaffine motions and move more erratically. We quantify these results using nearest neighbor changes as well as D²_min (Falk & Langer, PRE 1998).