RHEOLOGY OF LIQUID FOAMS

This paper further develops the model of the preceding paper, basing i tself on the fact that liquid films are of fundamental importance in e xplaining the behaviour of the liquid foam. The first step to bring th is to importance is illustrated by considering the liquid foam as comp osed of straight liquid films. The liquid foam is then modelled by eit her a Kelvin or Maxwell fluid. The simplicity of the model is emphasiz ed when considering large extensions or large compressions. The analys is is based on modelling the T1 process and taking into account the or ientation of the films. The key in determining the viscosity is the mo vement of cells when the T1 process occurs. The rate of T1 processes d etermines the motion of the cells which in tum will determine the visc osity. The calculation to determine the viscosity is performed using t he Boltzmann equation and the viscosity is found to be in the ideal ca se to have the form eta(f) is similar to eta(l)phi(g)-1/2.