Liquid flow in foams under microgravity

The motion of liquid in aqueous foams under low gravity conditions is governed by diffusion equations. Two models of liquid behaviour are analyzed and solved, corresponding to the limits of slip and non-slip interfaces in the Plateau border network. The motion of wetting fronts is given in detail, to enable comparison with experiments performed in, for example, parabolic flights or in space. Both show similar behaviour, except for the sharpness of the wetting fronts. The experiments analyzed include the constant input of liquid into a foam at a point, and the wetting of a dry foam from a liquid reservoir.