Title: Aggregation of athermal particles induced by capillarity

Author (Talk): Michael BERHANU, Clark University

Abstract:

Michael Berhanu, Arshad Kudrolli Aggregation of cohesive particles floating in a medium is a very broad physical phenomena occurring in colloidal systems, soot particles, and intergalactic dust under gravitation. We investigate the geometrically constrained dynamics of aggregation with new experiments using floating spheres at the air-liquid interface. A short range attractive force can be induced by careful choice of buoyancy and capillarity to create self-assembled particle structures which can be tracked by imaging. First, the particles are placed randomly at the interface, and then aggregation is induced by smoothly decreasing the area of the interface which causes the particles to come within the attractive force range caused by capillarity. The aggregation phenomena can be described as a a connectivity transition. Then to determine the effect of attraction on a two dimensional granular system, we study the structure of the aggregates with two-point correlation functions and their voronoi tesselation.