Numerical Study of Taylor Bubble Breakup by Placing Obstacle at 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 carried out by using the Volume-of-Fluid (VOF) multiphase model in ANSYS Fluent®. The Taylor bubble is formed at the upstream T-junction where air and water enter through two inlets perpendicular to each other. At the end of the channel, the Taylor bubble breaks up into two equal sizes 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. When X = 0 (i.e. the obstacle is positioned at the center), the symmetrical bubble breakup occurs and when X > 0 asymmetrical bubble breakup occurs. When the bubble breaks into unequal lengths, the length of the bifurcated bubble is higher along the outlet path opposite to that of the obstacle positioned. In this work, some parameters are calculated such as bubble length ratio, breakup length, breakup time and pressure drop. The result reveals that the bubble length ratio decreases as the obstacle height increases for a particular position of the obstacle. Similarly the breakup length and the breakup time decreases as the obstacle height increases for a particular obstacle position. From the results, it also observed that the pressure drop increases as the obstacle height increases for a particular position of the obstacle.