RHEOLOGY OF LIQUID FOAMS

This paper further develops the model of the preceding paper, basing itself on the fact that liquid films are of fundamental importance in explaining the behaviour of the liquid foam. The first step to bring this to importance is illustrated by considering the liquid foam as composed of straight liquid films. The liquid foam is then modelled by either a Kelvin or Maxwell fluid. The simplicity of the model is emphasized when considering large extensions or large compressions. The analysis is based on modelling the T1 process and taking into account the orientation of the films. The key in determining the viscosity is the movement of cells when the T1 process occurs. The rate of T1 processes determines the motion of the cells which in tum will determine the viscosity. The calculation to determine the viscosity is performed using the Boltzmann equation and the viscosity is found to be in the ideal case to have the form eta(f) is similar to eta(l)phi(g)-1/2.