On the structure of quasi-two-dimensional foams

Abstract

Bubble monolayers are widely used to probe the rheology of aqueous foams, and liquid content plays an important role in the response. We analyse the liquid distribution within three different types of two-dimensional foam, and predict (i) the rigidity loss transition in each case and (ii) the fraction of the bounding surfaces touched by the liquid network. The latter quantity allows the liquid fraction in an experiment to be determined non-invasively by image analysis.

Acknowledgements

For many years what we have termed the liquid–glass method was synonymous with the name of Manuel Fortes and the work of the Lisbon group. Manuel's enthusiasm and his prolific ideas will be missed. We thank K. Brakke for his development and maintenance of the Surface Evolver code, I. Cantat, N. Denkov and F. Graner for their insightful comments on this work and the participants in the Grenoble Foam Mechanics Workshop (2008) for their suggestions. E. Janiaud thanks D. Weaire and S. Hutzler for support, and ESA (MAP AO-99-108:C14914/02/NL/SH, MAP AO-99-075:C14308/00/NL/SH) for funding. S.J. Cox thanks the British Council Alliance programme, CNRS and EPSRC (EP/D048397/1, EP/D071127/1) for financial support.

Notes

Note

1. Following a suggestion by I. Cantat, we also recorded the width w _v of the inter-bubble films, in the sense parallel to the glass plate, which may give a better measure of film extent for small aspect ratios D/L. In the present study although w_v/L saturates to one at low liquid content, we gain no new information about the rigidity loss transition: the values of A_v and w_v go to zero together.