Dewetting of Thin Liquid Films Surrounding Air Bubbles in Microchannels

S. Khodaparast, O. Atasi, A. Deblais, B. Scheid, Howard A. Stone

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

As an air bubble translates in a microchannel, a thin film of liquid is formed on the bounding walls. In a microchannel with a rectangular cross-section, the liquid in the film leaks toward the low-pressure corners of the geometry, which leads to the appearance of local minima in the film thickness in the cross-sectional plane. In such a configuration, theory suggests that the minimum film thickness scales with Ca and Ca 4/3 depending on the distance from the nose of the bubble, where Ca = μU b /γ is the flow capillary number based on the bubble velocity U b , liquid viscosity μ, and surface tension γ, and Ca ≤ 1. We show that the film of a partially wetting liquid dewets on the channel wall at the sites of the local minima in the film thickness as it acquires thicknesses around and below 100 nm. Our experiments show that the distance L w between the nose of the bubble and the initial dewetting location is a function of Ca and surface wettability. For channels of different wettability, L w always scales proportional to Ca α , where 1.7 < α < 2 for the range of 10 -5 < Ca < 10 -2 . Moreover, L w increases up to 10 times by enhancing the wettability of the surface at a given Ca. Our present measurements of L w provide a design constraint on the lengths of bubbles to maintain a liquid wet channel without dry patches on the wall.

Original languageEnglish (US)
Pages (from-to)1363-1370
Number of pages8
JournalLangmuir
Volume34
Issue number4
DOIs
StatePublished - Jan 30 2018

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Wettability
Air
Nose
Surface Tension
Viscosity
Pressure

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Materials Science(all)
  • Spectroscopy
  • Surfaces and Interfaces
  • Electrochemistry

Cite this

Khodaparast, S. ; Atasi, O. ; Deblais, A. ; Scheid, B. ; Stone, Howard A. / Dewetting of Thin Liquid Films Surrounding Air Bubbles in Microchannels. In: Langmuir. 2018 ; Vol. 34, No. 4. pp. 1363-1370.
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Khodaparast, S, Atasi, O, Deblais, A, Scheid, B & Stone, HA 2018, 'Dewetting of Thin Liquid Films Surrounding Air Bubbles in Microchannels', Langmuir, vol. 34, no. 4, pp. 1363-1370. https://doi.org/10.1021/acs.langmuir.7b03839

Dewetting of Thin Liquid Films Surrounding Air Bubbles in Microchannels. / Khodaparast, S.; Atasi, O.; Deblais, A.; Scheid, B.; Stone, Howard A.

In: Langmuir, Vol. 34, No. 4, 30.01.2018, p. 1363-1370.

Research output: Contribution to journalArticle

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