Alexandros Askounis
International Institute for Carbon Neutral Energy Research, Kyushu University, Fukuoka, Japan;
Department of Mechanical Engineering, Kyushu University, Motooka 744, Nishi-ku, Fukuoka 819-0375, Japan; School of Engineering, University of East Anglia, Norwich, NR4 7TJ,UK
Huacheng Zhang
Department of Mechanical Engineering, Kyushu University, Fukuoka, Japan
Dejian Zhang
Department of Mechanical Engineering, Kitakyushu Institute of Technology, Kitakyushu, Japan
Yutaku Kita
Kyushu University, 744 Motooka, Nishi-ku, Fukuoka-shi, Fukuoka 819-0395, Japan; University of Edinburgh, King’s Buildings, Mayfield Road, Edinburgh EH9 3JL, United Kingdom
Gyoko Nagayama
Graduate school of Engineering, Kyushu Institute of Technology, Kitakyushu, Fukuoka 804-8550, Japan
Masamichi Kohno
Department of Mechanical Engineering, Thermofluid Physics Laboratory, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan; International Institute for Carbon-Neutral Energy Research (WPI - I2CNER), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
Yasuyuki Takata
Department of Mechanical Engineering, Thermofluid Physics Laboratory, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan; International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), 744 Motooka, Nishi-ku,
Fukuoka 819-0395, Japan
Khellil Sefiane
The University of Edinburgh, James Clerk Maxwell Building, Kings Buildings, School of Engineering, Edinburgh EH9 3FB, United Kingdom; Tianjin Key Lab of Refrigeration Technology, Tianjin University of Commerce, 300134
The existence of thermocapillary/Marangoni convection in pure water drops has been a hotly debated area over the last few years. In this paper, we report the induction of Marangoni convection in pure water drops by localized laser heating and visualized via high speed infrared and optical cameras. The optical camera recorded the evolution of drop shape over time and the infrared camera provided the spatiotemporal evolution of the temperature across the surface of the water drop. Localized heating induced a temperature gradient, which gave rise to a surface tension and eventually thermal and liquid flows within the drop. This flow manifested as twin vortices, which after experimental and theoretical arguments was attributed to Marangoni convection. We present, here, the influence of surface wettability which was found to play a major role in the convective patterns. Moreover, heating location and power on both the Marangoni convection patterns and the evaporation kinetics of the drops.