On a relation between foam and surface dilatational viscosities

Abstract

The significance of surface rheological properties in macroscopic foam rheological behavior is illustrated within the context of a pure foam dilatation. By application of the rheological theory of spatially periodic suspensions to a spatially periodic foam, the leading-order contribution to the macroscopic foam pressure tensor is shown to depend directly upon the rheological response of individual foam surfaces to globally induced deformation. Focusing upon a “wet” foam geometry within a pure foam dilatational motion enables us to determine a foam dilatational viscosity to leading order in the liquid-phase volume fraction as a function of surface dilatational viscosity as well as of thin foam film parameters such as the disjoining pressure.