Elastic dilatancy in wet foams: A simple model

Dilatancy as discovered by Osborne Reynolds refers traditionally to a volume expansion related to shear in the theory of granular media [O. Reynolds, Philos. Mag. 20 (1985) 469] [1]. However, it is also a feature of liquid foams: static dilatancy has been demonstrated from numerical and theoretical studies [D. Weaire, S. Hutzler, Philos. Mag. Lett. 83 (23) (2003) 2747-2760] [2]. Here, we analyse a simple theory for dilatancy using a variational principle based on the minimization of the variation of the enthalpy for a wet foam under shear.