Modeling interaction between a Taylor bubble and small bubble in a rectangular column

Abstract

The slip of a small bubble (SB) from the annular film of the slug/Taylor bubble (TB) is often encountered in the chemical reactors and has intrigued many researchers. A combined experimental and numerical study has been performed to investigate the interaction of the SB and the slug bubble in a rectangular column with viscous fluids. The interaction behavior of the SB depends upon its diameter, deq, and thermo-physical properties of the fluid. The SB sprints away from the slug bubble at low Morton numbers, Mo=ρl−ρggμ4/ρl2σ3 (sprint-away regime). On the other hand, SB interacts with TB due to its lower terminal velocity at higher Mo (bubble slip regime). The SB behaves independently ahead of the TB nose but accelerates linearly into its annular film. A regime map has been proposed to differentiate between the bubble slip and the sprint-away regime. The entrapped film between TB and SB is continuously fed from the annular film and avoids the coalescence. An ad hoc pressure jump model has been proposed to explain the repulsion of SB in the annular film. Furthermore, a modified lubrication theory based model predicted the stability of the entrapped film due to interfacial velocities and curvature.