Flow Instabilities during the Rise of a Bubble in a Narrow Tube: Shape Oscillation and Wake Formation

In this paper, the flow instabilities during the rise of asingle bubble in a narrow vertical tube are studied usinga transient 2D/axisymmetric model. These instabilitiesinclude the oscillation of the bubble shape and formation of a wake behind it. In the model, equations in addition to an advection equation Navier-Stokes for liquid volume fraction are solved. A modifiedVolume-of-Fluid (VOF) technique based on Youngs’algorithm is used to track the liquid/gas interface. Themodel results are validated by a comparison withavailable measurements [1]. The effect of different parameters such as surface tension and viscosity ofliquid are investigated.