Numerical study of bubble break-up in bubbly flows using a deterministic Euler–Lagrange framework

Abstract

In this work we present a numerical model to predict the bubble size distribution in turbulent bubbly flows. The continuous phase is described by the volume-averaged Navier–Stokes equations, which are solved on an Eulerian grid, whereas the dispersed or bubble phase is treated in a Lagrangian manner, where each individual bubble is tracked throughout the computational domain. Collisions between bubbles are described by means of a hard-sphere model. Coalescence of bubbles is modeled via a stochastic inter-particle encounter model. A break-up model is implemented with a break-up constraint on the basis of a critical Weber value augmented with a model for the daughter size distribution. A numerical parameter study is performed of the bubble break-up model implemented in the deterministic Euler–Lagrange framework and its effect on the bubble size distribution (BSD) is reported. A square bubble column operated at a superficial gas velocity of 2cm/s is chosen as a simulation base case to evaluate the parameters. The parameters that are varied are the values of the critical Weber number (Wecrit), the daughter size distribution (β) and the superficial gas velocity (vsup). Changes in the values of Wecrit and vsup have a significant impact on the overall BSD, while a different shaped β did not show a significant difference.