8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

Fri 911:10-14:00P6.1Liquid foams under gravityMaestro Armando, 1 Drenckhan Wiebke, 2 Langevin Dominique, 2 Höhler Reinhad, 3and Rio Emmanuelle 41 Laboratoire de Physique des Solides. Université Paris Sud 11, UMR 8502, Bat. 510,Orsay 91405 cedex, France, 91405, Orsay, France2 Laboratoire de Physique des Solides. Université Paris Sud 11, Orsay, France3 Institute des Nanosciences de Paris, Université Pierre et Marie Curie, Paris,France4 Laboratoire de Physique des Solides. Université Paris Sud 11, Paris, FranceLiquid foams consist of tightly packed gas bubbles separated by a continuous liquid phase. Thecompetition between gravity forces draining the liquid from in between the bubbles and capillaryforces resisting bubble deformation leads to a well-defined equilibrium profile of the liquidfraction f of a foam under gravity. Unfortunately, up to now, experimentally validated models ofthis profile only exist for foams of reasonably low liquid fraction (f < 10 %) whereas it is ofgreat importance for many scientific and industrial purposes to describe it for all types of liquidfoams (mono- vs. polydisperse, ordered vs. disordered) and for all liquid fractions. Our goalhere is therefore to provide a model which describes to a good approximation a much widerrange of liquid fractions and foam structures. For this purpose, we performed experiments onwell-characterized foams, which - wherever possible - we contrast with computer simulations.For most purposes we use monodisperse foams (between 50 µm and 10 mm). Dependingon the protocol of generation, such kind of foams are either disordered or self-ordered intohighly periodic structures, whose nature depends on the liquid fraction of the foam [1, 2]. Weestablish the profile using a conductivity technique [3]. Besides the practical importance ofa satisfying description of the liquid fraction profile by itself, it provides an important testbed of our understanding of the influence of the foam structure on its ”osmotic pressure” [4] ,which is related to the work required to elastically deform the bubbles upon the extraction of liquid.[1] Hoehler, R. ; et al. , Langmuir 2007, 24 (2), 418-425.[2] Van der Net, A. ; et al. , Soft Matter 2006, 2 (2), 129-134.[3] Feitosa, K. ; et al. , J. Phys. -Condes. Matter 2005, 17 (41), 6301-6305.[4] Princen, H. M. , Langmuir, 2, 519, 1986.1