The dynamic behavior of a droplet flows through a constricted splitting channel: a lattice Boltzmann study

Abstract

In this paper, a lattice Boltzmann method is used to simulate the dynamic behavior of a droplet flows through a constricted channel, where an obstacle is placed in the center of the constricted channel to split the droplet. The method is first used to simulate the effect of the capillary number Ca on the volume of the divided daughter droplets. Results show that the volume difference between the daughter droplets above and below the obstacle increases as Ca increases. We also find that reducing the capillary number is conducive to the droplet splitting into two daughter droplets with similar volume. The method is then used to simulate the influence of the viscosity ratio λ on the droplet flows through a constricted channel. As λ increases, the volume difference between the daughter droplets above and below the obstacle decreases. Finally, the influence of the confinement ratio Wc on the evolution of the droplet morphology is investigated. With increase in Wc, the volume difference between the daughter droplets above and below the obstacle increases. When Wc≥1, the droplet does not break up and completely enters the bottom channel. Comparing with the converging-diverging and ratchet channels, the constricted splitting channel is more conductive to the breakup of the droplet neck.