Dynamics of 3D Real Foam Coarsening

Abstract

Dynamics of a polydisperse 3D dry foam was experimentally investigated by means of a novel nondestructive method, more precisely by optical tomography associated to a foam reconstruction algorithm. The foam coarsening law obeys to a 3D extension of the classical von Neumann coarsening law of 2D foams. It is obtained as $〈{V}_{f}{〉}^{\ensuremath{-}1/3}d〈{V}_{f}〉{/dt\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}k}^{\ensuremath{'}}(f\ensuremath{-}〈f〉)$. $〈{V}_{f}〉$ is the mean volume of $f$-faced bubbles, ${k}^{\ensuremath{'}}$ a diffusion constant equal to the single film gas diffusion coefficient, and $〈f〉$ is the mean number of faces per bubble.