EXPERIMENTAL AND NUMERICAL STUDY OF MARANGONI CONVECTION IN A SANDWICHED DROPLET
Abstract
This research studies velocity fields resulted from the marangoni effect in a microscale droplet sandwiched in parallel plates. Surface tension becomes the dominant driving force as opposed to body forces as we move from the macroscale to microscale. Surface tension gradient is required to generate marangoni convection. This could be produced by a temperature gradient along the meniscus of the drop. To study this interfacial phenomenon, indium tin oxide micro thin film heater is utilized to create the necessary temperature gradient. Pure marangoni effect is studied by suppressing the evaporation effect on fluid flow by using an ionic liquid (molten salt) as the working fluid. Flow patterns have been visualized using nylon seeding particles under a polarized light microscope. The temperature distribution and velocity of the particles have been obtained using liquid crystal thermography (LCT) and micro particle image velocimetry (μPIV). The experimental data was validated by finite element analysis in COMSOL Multiphysics software. With recent advancements in the study of thermocapillary effect, microfluidic applications utilizing marangoni convection are gaining momentum. Applications include thermocapillary pumps, micromixers, actuators and sensors.