# Bubbles Breakup and Coalescence Modeling

## Simulation of Bubbles Breakup and Coalescence in a Bubble Column Reactor

In this tutorial, we provide guidelines for modeling and simulation of gas bubbles breakup and coalescence in a gas-liquid axisymmetric bubble column reactor. We use Eulerian multiphase model coupled with population balance approach in our simulations. We simulate a population of six different bubble sizes.

### You will also learn how to do the following through this tutorial:

• Using the Eulerian multiphase model
• Modeling a two-phase, unsteady bubble column problem with the Eulerian multiphase model
• Using population balance model with six bubble sizes
• How to set the proper solver settings and solution monitors
• Also, post-processing and analyzing the resulting data for bubble size distribution

### Problem Description of Bubbles Breakup and Coalescence in a Bubble Column Reactor

In this tutorial, we model a 2D, axisymmetric air-water bubble column with the diameter of 0.29 m and height of 2 m. Air comes into the water column through an inlet at the bottom with a constant velocity of 0.02 m/s. Air bubbles have a diameter of 3 mm after injection.

Injected air results in a turbulent flow pattern in the liquid column. This pattern transports the bubbles throughout the column. Turbulence effects and collisions cause the bubbles break up and coalesce with each other. Therefore, various bubble sizes are formed. Mass transfer and reactions (such as Fischer-Tropsch synthesis process) that may occur between the air and the liquid are largely affected by the size distribution of bubbles. Therefore, finding bubbles size distribution is of great importance in modeling bubble column reactors. We use population balance model to determine bubbles size distribution in ANSYS Fluent.