Formation and uniformity of bubbles in highly viscous fluids in symmetric parallel microchannels

Abstract

This work focuses on the formation and uniformity of bubbles in highly viscous fluids in symmetric parallel microchannels by using a high-speed camera. Nitrogen and high viscous glycerol-water solution containing 0.3% SDS are used as the gas and liquid phases respectively. The interface evolution during bubble information is reported. The effects of liquid flow rates, liquid viscosities, gas pressures, and microchannel configurations on bubble size distribution are investigated based on the gas-liquid two-phase flow resistance model. It is found that the difference in the downstream resistance, the pressure fluctuation of the upstream channels, and the feedback effect of bubble behaviors in the cavity affect the uniformity of bubble size. In the configuration that the widths of the microchannels engineered according to Murray's law, the uniformity is better, under low gas pressures, high viscosities and flow rates of liquids. Finally, the prediction models of bubble size in both geometries are proposed.