Induction of Marangoni convection in pure water drops

Yutaku Kita, Alexandros Askounis, Masamichi Kohno, Yasuyuki Takata, Jungho Kim, Khellil Sefiane

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)

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).

Original languageEnglish
Article number171602
JournalApplied Physics Letters
Volume109
Issue number17
DOIs
Publication statusPublished - Oct 24 2016

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy (miscellaneous)

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