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Mixing enhancement by degenerate modes in electrically actuated sessile droplets

Bansal, Shubhi and Sen, Prosenjit (2016) Mixing enhancement by degenerate modes in electrically actuated sessile droplets. In: SENSORS AND ACTUATORS B-CHEMICAL, 232 . pp. 318-326.

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Official URL: http://dx.doi.org/10.1016/j.snb.2016.03.109


The dependence of oscillation dynamics of a sessile droplet on the actuation parameters (voltage and frequency) in AC electrowetting which leads to the manifestation of non-axisymmetric oscillation patterns were investigated through experiments and theoretical modeling. The symmetrical nature of the electrowetting force leads to a circular three phase contact line for low actuation voltages. At higher actuation voltages, despite of symmetrical actuation force the contact line showed a transition from axisymmetric to non-axisymmetric oscillations. We found a good match between the experimentally determined region in the actuation parameter space where non-axisymmetric modes are dominant and the theoretically modeled parametric instability region derived from the Mathieu equation. The results showed that these non-axisymmetric modes are degenerate sectoral modes defined by the spherical harmonic functions. In contrast to axisymmetric oscillations, for non-axisymmetric oscillations the variation of contact angle and base radius remained in-phase between successive resonant modes. Finally, mixing by these parametric oscillations was investigated and the best mixing time was approximately 2% of the diffusive mixing time. (C) 2016 Elsevier B.V. All rights reserved.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to the ELSEVIER SCIENCE SA, PO BOX 564, 1001 LAUSANNE, SWITZERLAND
Keywords: Droplet dynamics; Non-axisymmetric oscillations; Degenerate modes; Mixing; Electrowetting
Department/Centre: Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited: 16 Jun 2016 07:43
Last Modified: 16 Jun 2016 07:43
URI: http://eprints.iisc.ac.in/id/eprint/53993

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