Abstract
Stabilizing and destabilizing films of liquid by design is not a simple challenge to overcome. Megahertz-frequency surface acoustic waves (SAWs), which propagate in a solid substrate, may stabilize liquid films against capillary forces, which otherwise promote the film breakup and the dewetting of the substrate. Here we explore the contribution of SAWs to the dynamics of micron- and submicron-thick films of water, which intervene between a bubble and a solid substrate. The investigation in this paper was inspired by a previous theoretical work on the acoustic Landau-Levich coating problem, which predicts the onset of stable and unstable coating films under the excitation of SAWs. We observe that the parametric regime of the stable Landau-Levich coating film translates to stable water films in our experiments. Moreover, we observe that unlike previous experiments with silicon oil, water films do not collapse under the parametric regime of the unstable Landau-Levich coating film, but appear to remain stable. A key to this controversy appears to be the presence of the stabilizing, long range, electrical double layer force in water, which is anticipated to alter the film response to the SAW.
- Received 13 February 2019
- Accepted 30 September 2020
DOI:https://doi.org/10.1103/PhysRevFluids.5.114002
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