Droplet breakup of a high-viscosity-ratio system in a nonuniform temperature field under laser irradiation

Abstract

This study conducted experimental and simple numerical studies to investigate the effect of change in viscosity ratio on the dispersion progress in a two-phase immiscible fluid. The viscosity ratio of the fluid was successfully modified by supplying direct heat radiation from an infrared laser. In the experiment, polybutenes and polydimethylsiloxane silicone oils were used as the dispersed droplet and matrix phases, respectively, and the radiation from an infrared laser with an intensity ranging from 10.9 to 87.3\u2009W/cm2 was applied. The results show that the selective radiation-heating method using different radiation absorption coefficients against the infrared laser wavelength caused significant deformation of the droplet phase, reaching even the breakup point of the droplet. We further performed a numerical simulation of three-dimensional thermal conduction, including radiation heating, to estimate the temperature changes in the droplet phase. The results show that the droplet size significantly affects the heat absorption and temperature distribution of the system. Finally, we discuss a suitable radiation intensity on a nondimensional chart using the modified viscosity ratio and critical capillary number.