Soft Matter Seminar: Granular aggregates with capillary interactions

Friday, August 6, 2010 - 1:30pm - 2:30pm
Reiss 261A
Michael Berhanu
Clark University, Dept. of Physics

We consider assembly of identical spherical particles (of diameter about few millimeter) floating on the surface of a viscous liquid. Interface deformation and gravity create attractive interactions between particles, leading to capillary aggregation. Firstly, features of this phenomena are experimentally investigated for a small number of particles to understand self-organization of floating spheres. Then for a large number of particles, particle density is homogeneously increased. Dense aggregates are formed and structure of such a cohesive granular medium as a function of area fraction is investigated. Using Voronoi tesselation, heterogeneity is characterized. Moreover significant short range order is found. This two-dimensional example demonstrates that structure of an athermal system of attractive particles contrasts strongly with the cohesionless case. When density is increased, heterogeneity decreases and steric effects become more important compared to attraction of particles.

Host: Daniel Blair