The slow spreading of a viscous fluid film over a deep viscous pool

A model is introduced for the spreading of an isolated viscous foam film over a deep viscous fluid pool. The effects of the bubbles rising in the foam are neglected, but the O(1) alteration to the density and viscosity of the foam due to the bubbles are accounted for. It is assumed that the foam phase is well modelled by the Stokes-flow equations. By exploiting the slenderness of the spreading layer, asymptotic techniques are used to analyse …