Induction of Marangoni convection in pure water drops

Kita, Yutaku, Askounis, Alexandros, Kohno, Masamichi, Takata, Yasuyuki, Kim, Jungho and Sefiane, Khellil (2016) Induction of Marangoni convection in pure water drops. Applied Physics Letters, 109 (17). ISSN 0003-6951

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Abstract

We report on experimental observations/visualization of thermocapillary or Marangoni flows in a pure water drop via infrared thermography. The Marangoni flows were induced by imposing a temperature gradient on the drop by locally heating the substrate directly below the center with a laser. Evidently, a temperature gradient along the liquid-air interface of ca. 2.5 °C was required for the Marangoni flows to be initiated as twin vortices and a subsequent gradient of ca. 1.5 °C to maintain them. The vortices exhibited an oscillatory behavior where they merged and split in order for the drop to compensate for the non-uniform heating and cooling. The origin of these patterns was identified by comparing the dimensionless Marangoni and Rayleigh numbers, which showed the dominance of the Marangoni convection. This fact was further supported by a second set of experiments where the same flow patterns were observed when the drop was inverted (pendant drop).

Item Type: Article
Related URLs:
Depositing User: LivePure Connector
Date Deposited: 12 Sep 2018 10:30
Last Modified: 12 Sep 2018 10:30
URI: https://ueaeprints.uea.ac.uk/id/eprint/68235
DOI: 10.1063/1.4966542

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