Coalescence of dry foam under water injection
Abstract
When a small volume of pure water – typically a drop – is injected within an aqueous foam, it locally triggers
the rupture of foam films, thus opening an empty cavity in the foam's bulk. We consider the final shape of
this cavity and we quantify its volume as a function of the volume of injected water, the diameter of the
bubbles and the liquid fraction of the foam. We provide quantitative understanding to explain how and
when this cavity appears. We epitomize the dilution of surfactants at the water–air interfaces as the main
cause lying behind the coalescence process. We identify a new coalescence regime for which a critical
surfactant concentration rules the stability of the foam.
Origin : Files produced by the author(s)
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