EFFECT of CAPILLARY NUMBER on DROPLET FORMATION REGIMES and DROPLET CHARACTERISTICS in a MICROFLUIDIC T-JUNCTION using OpenFOAM

This paper is aimed to investigate droplet formation mechanism of liquid/gas flow inside the T-junction microchannel. Various droplet formation regimes like squeezing, dripping and jetting regimes in low capillary number flows are investigated using the VOF model refined with smoothing operation to reduce spurious currents at the micro-scale. Effect of velocity field on droplet formation is studied. The results show that in squeezing regime, the effect of pressure build-up is more as compared to shear stress at gas/liquid interface. In dripping, shear force dominates over pressure; this is possible because of the small size of droplets compared to the channel width. In the end, the effect of capillary number on droplet characteristics such as slug length, the gap between slugs, the frequency of bubble formation and interfacial area is also investigated. It has been observed that microreactors should be operated at the low capillary number for efficient mass transfer.