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arXiv · 2005.12669

Three-dimensional dynamics of falling films in the presence of insoluble surfactants

Assen Batchvarov·Lyes Kahouadji·Cristian R. Constante-Amores·Gabriel Farah Norões Gonçalves·Seungwon Shin·Jalel Chergui·Damir Juric·Omar K. Matar
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Abstract

We study the effect of insoluble surfactants on the wave dynamics of vertically-falling liquid films. We use three-dimensional numerical simulations and employ a hybrid interface-tracking/level-set method, taking into account Marangoni stresses induced by gradients of interfacial surfactant concentration. Our numerical predictions for the evolution of the surfactant-free, three-dimensional wave topology are validated against the experimental work of Park & Nosoko (2003). The addition of surfactants is found to influence significantly the development of horseshoe-shaped waves. At low Marangoni numbers, we show that the wave fronts exhibit spanwise oscillations before eventually acquiring a quasi two-dimensional shape. In addition, the presence of Marangoni stresses are found to suppress the peaks of the travelling waves and preceding capillary wave structures. At high Marangoni numbers, a near complete rigidification of the interface is observed.

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Assen Batchvarov, Lyes Kahouadji, Cristian R. Constante-Amores, Gabriel Farah Norões Gonçalves, Seungwon Shin, Jalel Chergui, Damir Juric, Omar K. Matar. 2020-05-25. Three-dimensional dynamics of falling films in the presence of insoluble surfactants. https://doi.org/10.1017/jfm.2020.796

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