摘要
We conduct a computational fluid dynamics simulation to investigate the behaviors of bubble breakup in a microfluidic T-junction using volume-of-fluid method to represent the interface. The evolution of bubble mor- phology and the distributions of velocity and pressure in flow field are analyzed, and the effect of width ratio between main channel and branch on the bubble mor- phology are evaluated. The results indicate that, the ＂tun- nel＂ breakup, obstructed breakup, combined breakup and non-breakup are observed during the bubble flows through the T-junctions under different condition. The whole bub- ble breakup process undergoes the extension, squeeze and pinch-off stages, while the non-breakup process experi- ences extension and pushing stages. We find that, in the squeeze stage, a local vortex flow forms at the front edge of the bubble for the ＂tunnel＂ breakup while the velocity inside the bubble is of a parabolic distribution for the obstructed breakup. Irrespective of non-breakup regimes, there is a sudden pressure drop occurring at the gas-liquid interface of the bubble in the squeeze stage, and the pres- sure drop at the front interface is far larger than that at the depression region. The transition of the bubble breakup regime through the T-junction occurs with an increase in width ratio of main channel to the branch, which sequen- tially experiences the non-breakup regime, ＂tunnel＂ breakup regime and obstructed breakup regime. The flow regime diagrams are plotted with a power-law correlation to distinguish the bubble/droplet breakup and non-breakup regimes, which also characterize the difference between bubble and droplet breakup through a T-junction.
我们进行计算液体动力学模拟用 volume-of-fluid 方法在 microfluidic T 连接调查水泡决裂的行为代表接口。水泡形态学的进化和流动地里的速度和压力的分布被分析，并且在水泡形态学上的主要隧道和分支之间的宽度比率的效果被评估。结果显示那，隧道决裂，妨碍的决裂，联合决裂和非决裂在不同状况下面通过 T 连接在水泡流动期间被观察。整个水泡决裂进程经历扩展，压榨并且拧离开阶段，当非决裂进程经历扩展，推上演时。当在水泡内的速度具有为妨碍的决裂的寓言的分布时，我们发现在 squeeze 阶段，本地旋涡流动为隧道决裂在水泡的前面边形成。不管非决裂政体，有突然的压力落下，在 squeeze 发生在水泡的煤气液体的接口舞台，和在前面接口的压力落下在消沉区域比那远大。通过 T 连接的水泡决裂政体的转变随主要隧道的宽度比率的增加发生到分支，它顺序经历非决裂政体，隧道决裂政体和妨碍的决裂政体。流动政体图与幂定律关联被阴谋区分水泡 / 微滴决裂和非决裂政体，它也通过 T 连接描绘水泡和微滴决裂之间的差别。
