A diffuse-interface model for electrowetting drops in a Hele-Shaw cell

H. W. Lu, Karl B Glasner, A. L. Bertozzi, C. J. Kim

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Abstract

Electrowetting has recently been explored as a mechanism for moving small amounts of fluids in confined spaces. We propose a diffuse-interface model for drop motion, due to electrowetting, in a Hele-Shaw geometry. In the limit of small interface thickness, asymptotic analysis shows that the model is equivalent to Hele-Shaw flow with a voltage-modified Young-Laplace boundary condition on the free surface. We show that details of the contact angle significantly affect the time scale of motion in the model. We measure receding and advancing contact angles in the experiments and derive their influence through a reduced-order model. These measurements suggest a range of time scales in the Hele-Shaw model which include those observed in the experiment. The shape dynamics and topology changes in the model agree well with the experiment, down to the length scale of the diffuse-interface thickness.

Original languageEnglish (US)
Pages (from-to)411-435
Number of pages25
JournalJournal of Fluid Mechanics
Volume590
DOIs
Publication statusPublished - Nov 11 2007

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ASJC Scopus subject areas

  • Mechanics of Materials
  • Computational Mechanics
  • Physics and Astronomy(all)
  • Condensed Matter Physics

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