MECHANISTIC STUDY OF LASER-DRIVEN DROPLET MIGRATION

Droplet thermocapillary migration is a typical scientific problem in microgravity fluid science, and the study of microgravity droplet dynamics not only has the theoretical significance of fluid mechanics, but also has important practical value. A two-dimensional axisymmetric laser-driven droplet migration model was established. The laser-driven droplet migration process in microgravity environment is studied by simulation calculations, and the effects of droplet diameter and mother liquor parameters on droplet migration speed and behavior are investigated. Firstly, the migration of the droplets was studied when the mother liquor and the droplets have smaller laser coefficients and the initial positions of the droplets are different; then the migration of the droplets was studied the mother liquor has a smaller laser absorption coefficient and the droplets have a larger laser absorption coefficient and the ratios of the diameter to the width of the mother liquor are different. Simulation results show that when the absorption coefficients of both mother liquor and droplet for laser are small, the direction of droplet migration is mainly influenced by the initial position of the droplet. When the absorption coefficient of the mother liquor to the laser is small and the absorption coefficient of the droplet to the laser is large, the droplet will move toward the laser. The initial position of the droplet has less influence on the migration direction, but the ratio of the droplet diameter to the width of the mother liquor will affect the droplet migration behavior. By comparing with the YGB theory, the simulation results are consistent with the trend of the theoretical results. The physical mechanism of laser-driven droplet migration is studied, the mechanism of interfacial tension effect is explored, the law of laser-driven droplet migration is obtained, and the driving control method for droplets is explored.