Modeling the dynamics of an oil drop driven by a surface acoustic wave in the underlying substrate

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Hauptverfasser: Fasano, M., Li, Y., Diez, J. A., D'Addesa, J., Manor, O., Cummings, L. J., Kondic, L.
Format: Preprint
Veröffentlicht: 2023
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author Fasano, M.
Li, Y.
Diez, J. A.
D'Addesa, J.
Manor, O.
Cummings, L. J.
Kondic, L.
author_facet Fasano, M.
Li, Y.
Diez, J. A.
D'Addesa, J.
Manor, O.
Cummings, L. J.
Kondic, L.
contents We present a theoretical study, supported by simulations and experiments, on the spreading of a silicone oil drop under MHz-frequency surface acoustic wave (SAW) excitation in the underlying solid substrate. Our time-dependent theoretical model uses the long wave approach and considers interactions between fluid dynamics and acoustic driving. While similar methods have analyzed micron-scale oil and water film dynamics under SAW excitation, acoustic forcing was linked to boundary layer flow, specifically Schlichting and Rayleigh streaming, and acoustic radiation pressure. For the macroscopic drops in this study, acoustic forcing arises from Reynolds stress variations in the liquid due to changes in the intensity of the acoustic field leaking from the SAW beneath the drop and the viscous dissipation of the leaked wave. Contributions from Schlichting and Rayleigh streaming are negligible in this case. Both experiments and simulations show that after an initial phase where the oil drop deforms to accommodate acoustic stress, it accelerates, achieving nearly constant speed over time, leaving a thin wetting layer. Our model indicates that the steady speed of the drop results from the quasi-steady shape of its body. The drop speed depends on drop size and SAW intensity. Its steady shape and speed are further clarified by a simplified traveling wave-type model that highlights various physical effects. Although the agreement between experiment and theory on drop speed is qualitative, the results' trend regarding SAW amplitude variations suggests that the model realistically incorporates the primary physical effects driving drop dynamics.
format Preprint
id arxiv_https___arxiv_org_abs_2312_12367
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Modeling the dynamics of an oil drop driven by a surface acoustic wave in the underlying substrate
Fasano, M.
Li, Y.
Diez, J. A.
D'Addesa, J.
Manor, O.
Cummings, L. J.
Kondic, L.
Fluid Dynamics
We present a theoretical study, supported by simulations and experiments, on the spreading of a silicone oil drop under MHz-frequency surface acoustic wave (SAW) excitation in the underlying solid substrate. Our time-dependent theoretical model uses the long wave approach and considers interactions between fluid dynamics and acoustic driving. While similar methods have analyzed micron-scale oil and water film dynamics under SAW excitation, acoustic forcing was linked to boundary layer flow, specifically Schlichting and Rayleigh streaming, and acoustic radiation pressure. For the macroscopic drops in this study, acoustic forcing arises from Reynolds stress variations in the liquid due to changes in the intensity of the acoustic field leaking from the SAW beneath the drop and the viscous dissipation of the leaked wave. Contributions from Schlichting and Rayleigh streaming are negligible in this case. Both experiments and simulations show that after an initial phase where the oil drop deforms to accommodate acoustic stress, it accelerates, achieving nearly constant speed over time, leaving a thin wetting layer. Our model indicates that the steady speed of the drop results from the quasi-steady shape of its body. The drop speed depends on drop size and SAW intensity. Its steady shape and speed are further clarified by a simplified traveling wave-type model that highlights various physical effects. Although the agreement between experiment and theory on drop speed is qualitative, the results' trend regarding SAW amplitude variations suggests that the model realistically incorporates the primary physical effects driving drop dynamics.
title Modeling the dynamics of an oil drop driven by a surface acoustic wave in the underlying substrate
topic Fluid Dynamics
url https://arxiv.org/abs/2312.12367