Numerical Simulation of Bubble Coalescence using a Volume of Fluid (VOF) Model

This paper presents a Volume Tracking model developed with the specific objective of studying the time – dependent behavior of multiple, “large” gas bubbles rising in an initially quiescent liquid. The model, based on the Volume – Of – Fluid concept, employs an advanced interface tracking scheme known as Youngs’ VOF to advance the gas – liquid interface through the Eulerian mesh. Additionally, the model solves the incompressible Navier – Stokes equations to obtain the flow field. Results obtained for four different cases will be discussed: the formation and rise of a skirted bubble and of a spherical cap bubble, the coalescence of two identical gas bubbles and the behavior of two gas bubbles emanating from two adjacent orifices. It could be concluded that the Volume Tracking model is able to track the motion of a gas – liquid interface, subject to appreciable changes in its topology, embedded in a flow field with significant vorticity.