Kalichetty Srinivasa Sagar
Department of Mechanical Engineering, IIT Madras, Chennai, India
Daniel Orejon
International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan; Department of Mechanical Engineering, Thermofluid Physics Laboratory, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan; Institute for Multiscale Thermofluids, The School of Engineering, The University of Edinburgh, Edinburgh EH9 3JL, United Kingdom
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
Sivasankaran Harish
International Institute for Carbon-Neutral Energy Research (WPI - I2CNER), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan; The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-8656, Japan
Sumitomo Hidaka
Faculty of Engineering, Kyushu University, Motooka 744, Nishi-ku, Fukuoka 819-0395, Japan; Department of Mechanical Engineering Science, Kyushu University, Fukuoka 812-8581, Japan
Arvind Pattamatta
Heat Transfer and Thermal Power Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, Tamil Nadu, India
Sundararajan Thirumalachari
Department of Mechanical Engineering, Indian Institute of Technology Madras,
Chennai-600036, India
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
Actuation of water droplets by thermocapillary phenomenon
is quite challenging due to typically large contact angles and the associated contact angle hysteresis. The present study demonstrates the migration of water droplets over UV treated TiO2 based superhydrophilic surfaces characterized by near 0° contact angle. This technique has a merit of migrating water droplets with moderate temperature gradients without the need for expensive microfabrication procedures and/or patterned wettability microheaters. The influence of droplet volume on the temporal evolution of the velocity is studied for 2µl and 6µl droplets. The
thermocapillary and spreading effects on water droplet migration dynamics are qualitatively explained. Further, fluid flow and heat transfer phenomena inside the droplet during migration are elucidated from emerging thermal patterns captured using infrared (IR) thermography.