Drainage induced convection rolls in foams

Hutzler, S., Cox, S.J., Janiaud, E. and Weaire, D. (2007) Drainage induced convection rolls in foams. Colloids and Surfaces A: Physicochemical and Engineering Aspects Volume 309, Issues 1-3, 1 November 2007, Pages 33-37 A Collection of Papers Presented at the 6th Eufoam Conference, Potsdam, Germany, 2-6 July, 2006 Sponsorship: European Space Agency (14914/02/NL/SH, 14308/00/NL/SG) (AO-99-031) CCN 002 MAP Project AO-99-075); Science Foundation Ireland (RFP 05/RFP/PHY0016); Royal Society; UWA Learned Societies.

Forced drainage describes the procedure in which liquid is added to a column of foam at a constant flow rate. For sufficiently high flow rates this results in a convective bubble motion, the symmetry of which depends on the experimental details. We review recent experiments, in particular for the case of convection in a foam column which is tilted away from the vertical. The experimentally-determined dependency of the onset of convection with the tilt angle is well described by a combination of standard drainage theory and simple foam rheology. We also present experimental data for foam convection in a Hele-Shaw cell. The measured foam density and velocity profiles provide an excellent basis upon which to develop a theory of the phenomenon.

Peer reviewed