Approaching the dry limit in foam

The approach to the dry limit of a foam is analysed within the model of constant surface tension and negligible film thickness. Higher-order corrections to the commonly assumed asymptotic forms of energy and shear elastic modulus are identified. These are discussed in terms of an approximate model in which the effect of finite liquid fraction is represented by a negative line tension associated with Plateau borders. In implementing this numerically, care has to be taken to eliminate unstable short-wavelength modes of deformation.