Rayleigh-Taylor-like instability in a foam film
Résumé
It is well known, since the seminal work of Mysels et al., that the thinner parts of a foam film go up by gravity, whereas the thicker parts go down. Preparing a foam film in a controlled way, so that the top part of the film is much thicker than the bottom part at initial time, we show that this situation is indeed unstable under gravity. The observed instability is identified as a Rayleigh-Taylor like instability and studied in the linear regime. The wavelength and the growth rate are measured as a function of the effective gravity, and as a function of the thick film extension. We theoretically show that all wavelengths are unstable, as the surface tension stabilizing the small wavelengths in the classical bulk Rayleigh Taylor instability has no significant equivalent in a foam film. The fastest mode is analytically determined and is in qualitative agreement with the experimental observations.
Domaines
Matière Molle [cond-mat.soft]
Fichier principal
Shabalina et al-2019-Rayleigh-Taylor-like instability in a foam film.pdf (4.6 Mo)
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