Eur. Phys. J. E 11, 29-35 (2003)
DOI: 10.1140/epje/i2002-10126-9

Topological changes in a two-dimensional foam cluster

S.J. Cox¹, M.F. Vaz² and D. Weaire<sup>1

1</sup>  Physics Department, Trinity College, Dublin 2, Ireland
²  Instituto de Ciência de Materiais e Superfícies and Departamento de Engenharia de Materiais, Instituto Superior Técnico, Av. Rovisco Pais, 1096 Lisboa Codex, Portugal

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(Received 18 October 2002 / Received in final form 19 March 2003 / Published online: 21 May 2003)

Abstract
Experiments on a small cluster of bubbles in a nominally two-dimensional foam show an instability in which a topological change forces one of the bubbles to be ejected to the outside of the cluster at a point where this is not predicted by a two-dimensional model of a foam. This is interpreted in terms of the energy of the initial and ejected states and of the finite liquid content of the experimental system. A description of the distribution of liquid in various experimental set-ups suggests that the exact response may depend critically upon the type of system used. This is demonstrated experimentally with reference to small clusters of bubbles undergoing a single topological change.

PACS
82.70.Rr - Aerosols and foams.
46.32.+x - Static buckling and instability.

© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2003