Cross-Stream Thermocapillary Migration of a Droplet in a Confined Oscillatory Flow

Abstract The study of cross-stream migration of droplets in a confined oscillatory flow turns out to be of significant importance in various physiological systems. Although significant exploration has been done on the thermocapillary migration of droplets in a pressure-driven flow, a linear superposition of time-dependent flow oscillations would not be suitable to address the nonlinearity due to channel confinement and interfacial deformation. The present study numerically investigates the role of an externally imposed temperature gradient on the manipulation of droplets suspended in such a flow field. The effect of channel confinement and flow-induced shape deformation is also presented. It is observed that a droplet, suspended in an oscillatory imposed flow, exhibits cross-stream migration toward the upper hot wall at a comparatively lower imposed lateral temperature gradient than in a system without any flow pulsation. The numerical model presented herein offers a robust framework for droplet manipulation in a nonisothermal oscillatory flow field and has significant applications in different biomicrofluidic applications with an imposed oscillatory flow.