Studies of the Movement Mechanism of Droplets in Power-Law Fluids in a T-Junction Microchannel by the Lattice Boltzmann Method

Abstract

The movement mechanisms of Newtonian droplets in power-law fluids in T-junction microchannels were studied with the lattice Boltzmann method. The effects of power-law index <i>n</i> , capillary number <i>C</i>_a, flow ratio <i>Q</i> , viscosity ratio <i>M</i>, and surface wettability <i>θ</i> on the droplet formation size, the formation time and the deformation index (<i>D</i>_I) were investigated in detail. The results show that, first, with the increase of power-law index n from 0.4 to 1.6, the droplet formation size decreases almost linearly, and both the droplet formation time and the deformation index decrease quickly at first and then much more slowly. Second, the influences of the viscosity ratio on the droplet formation size, the formation time and the deformation index are basically the same as those of the power law index. In addition, with the increases of <i>C</i>_a and <i>θ</i> of the main channel, the droplet formation size decreases almost linearly, while the droplet formation time and deformation index decrease rapidly at first and then slowly, and the decreasing rates weaken with the increase of the power-law index. At last, with the increase of flow ratio <i>Q</i> of the continuous phase over the dispersed phase, the droplet formation size increases, and the droplet formation time as well as the deformation index decrease.