Numerical Study of Taylor Bubble Breakup by Placing Obstacle at the T-Junction Bifurcation

Abstract

A two-dimensional numerical study of Taylor bubble breakup is carried out, where Taylor bubble flows in a horizontal T-section microchannel with T-junction bifurcation. The numerical simulation is performed using the Volume-of-Fluid multiphase model using commercially available ANSYS Fluent®. The Taylor bubble is formed at the upstream T-junction where air and water enters through two inlets perpendicular to each other. At the end of the channel, the Taylor bubble breaks up symmetrically into two equal size at the bifurcated T-junction. For controlled breakup of the Taylor bubble into two unequal lengths, an obstacle is positioned at the T-junction bifurcation to which the Taylor bubble strikes. The bubble breakup will be symmetrical, asymmetrical or no breakup depending on the position and height of the obstacle. In this work, the obstacle position varied from X = 0 to 0.1 mm, where X is the distance from the center of T-junction bifurcation to the obstacle, and height is varied from Y = 0.05 to 0.2 mm. The symmetrical breakup of the bubble occurs when there is no obstacle, due to the equally distributed flow rate. The symmetrical breakup process also occurs when the obstacle positioned at the center of the T-junction bifurcation irrespective of the height of the obstacle. When the obstacle position shifted to one side of the T-junction bifurcation, asymmetrical bubble breakup takes place. This occurs because, as the obstacle shifted to one side (say right side) of the T-junction bifurcation, the right side opening decreases and the resistance to flow increases. So, the bubble breaks into two unequal lengths. The length of the bifurcated bubble is higher along the outlet path opposite to that of the obstacle position. When the opening on one side of the obstacle decreases beyond some threshold value, the bubble will not be able to pass through this opening and will result in no bubble breakup.