A strategy for regulation of gas-liquid microflow patterns by changing gas kinetic energy

Controllable regulation of gas-liquid microflow pattern and bubble size is significant to bubble-based microfluidics, but it is hard to be realized with the existing technologies. Accordingly, this work reports a convenient strategy that changes the gas kinetic energy to controllably regulate the microflow patterns from Taylor flow to short bubble flow and bubbly flow. Results exhibit that the desired flow patterns and bubble size can be effectively obtained by varying the gas inlet size to change gas kinetic energy, and a much wider bubbly flow regime which could not be reached normally in conventional T-junction microchannels is easily obtained. Besides, from the bubble's characteristic width and length, the behaviors of the bubble generation in different Tjunctions were compared to reveal the mechanism behind the generation of bubbles. Importantly, as the hydraulic diameter of the gas inlet decreases from 365.0 to 50.0 pm, the dominative factors on the bubble generation transfer mainly from the liquid phase to both the two-phases because the gas-liquid Weber number ratio increases from 6.6 x 10- 5-5.4 x 10-3 to 4.2 x 10- 2-3.4. Finally, the parameter of the two-phase Weber number ratio is the first time introduced to the unified prediction model for bubble generation frequency.