The bubble breakup process and behavior in T-type microchannels

Abstract

A double T-type microchannel consisting of two T-junctions is used as the base unit of tree-like microchannels. Studying the breakup process and behavior of bubbles in T-type microchannels can help enhance the capability of microfluidic systems and microchannel heat exchangers. In this study, the bubble breakup process in a double T-type microchannel was simulated using a volume of fluid model via numerical simulation. The simulation results show a total of five regimes of bubble breakup with capillary numbers between 0.001 and 0.008 and dimensionless bubble lengths between 1 and 9, which are the non-breakup, “tunnel” breakup, obstructed breakup, merging symmetric breakup, and merging non-breakup. These five breakup regimes were studied in detail. At a high velocity of the gas phase and with a small size of the generated bubble, the bubble does not break up. Symmetric breakup regimes can be divided into two regimes: tunnel breakup and obstructed breakup. Shear force plays a significant role in the tunnel breakup regime. The obstructed breakup regime is mainly caused by the increase in pressure at the T-junction, which elongates and makes the bubble break up. In the merging symmetrical breakup regime, the bubble has a tunnel breakup process at the beginning. The shear force is small and cannot break up the bubble. The merged bubble breaks up under the action of the obstructed breakup regime. Bubbles are in the merging non-breakup regime mainly because they are too long to break up.