“Marginal pinching” in soap films
Physique de la Matière Condensée,
CNRS URA 792, Collège de France 11, place Marcelin Berthelot, 75231 Paris Cedex 05, France
Corresponding author: Achod.Aradian@college-de-france.fr
Accepted: 3 July 2001
We discuss the behaviour of a thin soap film facing a frame element: the pressure in the Plateau border around the frame is lower than the film pressure, and the film thins out over a certain distance , due to the formation of a well-localized pinched region of thickness h(t) and extension w(t). We construct a hydrodynamic theory for this thinning process, assuming a constant surface tension: Marangoni effects are probably important only at late stages, where instabilities set in. We find , and for the pinch dimensions, and . These results may play a useful role for the discussion of later instabilities leading to a global film thinning and drainage, as first discussed by K. Mysels under the name “marginal regeneration”.
PACS: 68.15.+e – Liquid thin films / 83.80.Iz – Emulsions and foams / 02.40.Xx – Singularity theory
© EDP Sciences, 2001