A note on the effects of liquid viscoelasticity and wall slip on foam drainage

A foam drainage model is modified to attempt the description of foams made of viscoelastic liquids (such as polymer solutions). In particular, the standard approach to foam drainage dominated by viscous dissipation in Plateau borders is modified to take into account the elastic forces acting on the fluid within Plateau borders, and slipping of the polymer solution at the walls of Plateau borders. It is shown that, in the case of forced drainage, the resulting differential equations reduce to the same one obtained in the case of Newtonian liquids, which is satisfied by the well-known solitary wave solution. According to these results, the fluid elasticity has no effect on the drainage velocity, while the wall slip assumption is compatible with recent observations showing a faster drainage velocity in the forced drainage experiment.