Lattice Boltzmann simulation of droplet formation in T-junction and flow focusing devices

• Droplet formation in T-junction microchannel and flow focusing configuration is studied by lattice Boltzmann method.
• Parameters including flow rate ratio, capillary number, geometry, and wetting property are investigated.
• Geometry effect plays a significant role in determination of shape, length and diameter of droplets.

Droplet formation in T-junction microchannel and flow focusing configuration is numerically studied by using the lattice Boltzmann method. Various parameters including flow rate ratio, capillary number, geometry, and wetting property are investigated. The results show that due to the confinement of the main channel, the T-junction microchannel is prone to generate elliptic droplets, while the flow focusing configuration is likely to generate spherical droplets. In particular, the work shows that the geometry effect, i.e., the width ratio of main channel to lateral channel of T-junction, and the width of the orifice in flow focusing configuration, plays a significant role in the determination of shape and length or the diameter of droplets. It also demonstrates that the lattice Boltzmann method with free energy model is an effective way to simulate the generation of droplets in T-junction microchannel as well as in flow focusing configuration.