Taylor Bubble Generation Rules in Liquids with a Higher Viscosity in a T-Junction Microchannel

Generation of bubbles in a T-junction microdevice is vital to microfluidic applications for its advantages of easy fabrication and scaling-up, but the bubble generation in liquids with a higher viscosity in the T-junction is rarely reported for the unstable dispersion behavior under the constant flow rate-driven condition. Accordingly, this work investigates the bubble generation rules in liquids with a higher viscosity (45.6–240.5 mPa·s) under the constant-pressure method. It shows that the bubble formation process in higher viscous liquids contains three stages, expansion, shrinking, and necking, which are obviously different from the filling and squeezing stages in the lower viscous liquid. Importantly, the generation of satellite bubbles as a new bubble generation performance could be observed for the first time in the gas–liquid microdispersion process. The new dispersion mechanism and some novel phenomena are revealed by the interface evolution rules. Finally, a novel mathematical model is developed to predict the bubble length.