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Issue 14, 2016
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Electrokinetics of isolated electrified drops

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Abstract

Using a recently developed multiphase electrokinetic model, we simulate the transient electrohydrodynamic response of a liquid drop containing ions, to both small and large values of electric field. The temporal evolution is found to be governed primarily by two dimensionless groups: (i) Ohnesorge number (Oh), a ratio of viscous to inertio-capillary effects, and (ii) inverse dimensionless Debye length (κ), a measure of the diffuse regions of charge that develop in the drop. The effects of dielectric polarization dominate at low Oh, while effects of separated charge gain importance with increase in Oh. For small values of electric field, the deformation behaviour of a drop is shown to be accurately described by a simple analytical expression. At large electric fields, the drops are unstable and eject progeny drops. Depending on Oh and κ this occurs via dripping or jetting; the regime transitions are shown by a Oh–κ phase map. In contrast to previous studies, we find universal scaling relations to predict size and charge of progeny drops. Our simulations suggest charge transport plays a significant role in drop dynamics for 0.1 ≤ Oh ≤ 10, a parameter range of interest in microscale flows.

Graphical abstract: Electrokinetics of isolated electrified drops

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Publication details

The article was received on 07 Jan 2016, accepted on 26 Feb 2016 and first published on 26 Feb 2016


Article type: Paper
DOI: 10.1039/C6SM00047A
Citation: Soft Matter, 2016,12, 3310-3325
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    Electrokinetics of isolated electrified drops

    R. Pillai, J. D. Berry, D. J. E. Harvie and M. R. Davidson, Soft Matter, 2016, 12, 3310
    DOI: 10.1039/C6SM00047A

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