Numerical simulation of the bubble dynamics in a bifurcated micro-channel using the lattice Boltzmann method

摘要

The dynamics behavior of a bubble passing through a bifurcated microchannel is studied numerically by using the lattice Boltzmann model. The effects of channel wettability, the viscosity ratio, the capillary number (Ca), the initial bubble size, and the flow flux ratio on the interface dynamic behavior, breakup mechanism, and residual mass of the bubble through the bifurcated microchannel are studied systematically. The simulation result indicates that these factors have significant influence on the bubble motion behavior. The bubble splits into two sub-bubbles and flow out of the channel completely when the channel surface is hydrophilic. However, some mass residuals of the bubble are observed when the channel surface is hydrophobic and the residual mass increases with the contact angle. On the other hand, as the viscous ratio of gas-liquid increases, the bubble is more likely to break up and to flow out of the channel. In addition, for the case of low capillary number and small bubble size, the bubble cannot break up, so it finally strands in the main channel. Besides, as capillary number increases, the flow flux ratio required for the bubble to flow out of subchannels increases. Eventually, we establish the relation for the critical flow flux ratio Qc as Qc =0.604 e 13.44 C a and Qc = 1.985 e 5.53 C a to describe whether the bubble breaks up or not for different bubble radii.