Drainage-induced control of avalanches in foam coalescence
Résumé
Surfactant foams are particularly unstable because of avalanches of coalescence which lead to an instant collapse of considerable part of the foam volume when the liquid fraction falls below a critical value. In many applications it is crucial to control the occurence of these avalanches phenomena. In this study we compare the evolution of a foam made from a surfactant solution with a foam stabilized by a surface-active polymer and show that avalanches phenomena can be suppressed for the polymer stabilized foams for which a coalescence front slowly propagates between the top to the bottom of the foam. We demonstrate that the occurence and length-scale of avalanches is controlled by the liquid fraction profile in the foams which is set by the rate of drainage. Our study therefore illustrates the strong coupling between drainage and coalescence and provides means to control it by varying the type of foam stabilizer used.
Domaines
Matière Molle [cond-mat.soft]
Origine : Fichiers produits par l'(les) auteur(s)
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