Wiebke Drenckhan

Abstract:

Beyond being regular companions in daily life (from dishwashing and beer to shaving), liquid foams offer to the eyes of physicists a fascinating example of “athermal granular media” or “visco-elastic plastic yield-stress fluids”. The physical properties of these complex systems emerge from the multi-body interactions that arise in assemblies of strongly deformable gas bubbles, whose energy is essentially controlled by the interfacial energy of the gas/liquid interfaces. Nature’s attempt to minimize this energy leads to many intriguing properties of liquid foams which continue to challenge Soft Matter physicists in the attempt to describe reliably their morphology, flow behavior or stability. I will show in an illustrative example how some of this physics may be used to help art restorers in their challenging task to remove complex dirt from fragile surfaces. Inspired by this problem, I will discuss an open question on the influence of oil vapours on foam properties.