Capillary interactions between nearby interfacial objects

Institute for Computational and Experimental Research in Mathematics, Brown University - Providence, RI 02912, USA

Received: 29 January 2013
Accepted: 16 April 2013

Abstract

We develop a general method to study the capillary interactions between objects of arbitrary shape which float close to each other on an interface, a regime in which multipole expansion is not useful. The force is represented as a power series in the small distance between the objects, of which the leading order is finite. For objects with size a much larger than the capillary length l_c, the force scales as and the prefactor depends on the mean radius of curvature R at the closest points. After contact the objects roll and/or slide with respect to each other to locally maximize R and therefore the force. For smaller objects (, the force scales as , and the prefactor depends only weakly on the shape and relative orientation of the objects.