CFD Simulation of Internal Flow and Mixing within Droplets in a T-Junction Microchannel
Chao Xu, Feishi Xu, Chaoqun Yao, Tingting Liu, Guangwen Chen
Abstract
This work performed a three-dimensional numerical investigation on the effect of the viscosity ratio on the circulation topology and mixing inside droplets in a T-junction microchannel using the volume-of-fluid method. The results suggest that the recirculation zone shrinks at both ends of the droplet with increasing viscosity ratios, whereas it expands in the droplet’s main body. A modified non-dimensional circulation time was defined by considering the local circulation, which can better capture the influence of the viscosity ratio on the mixing intensity. The results show that the mixing intensity decreases with higher viscosity ratios, especially at the front end of the droplet. The mixing inside the droplets is limited mainly due to the isolation of the symmetrical recirculation vortices. Accordingly, an improvement to the T-junction was proposed to break the balance of the flow symmetry at the droplet formation stage, thus significantly enhancing the mixing intensity.