Eulerian-Eulerian two fluid model numerical simulation of bubbly flows coupled with heat and mass transfer

Abstract

Turbulent two-phase bubbly flows occur in a variety of chemical, biochemical, and energy industrial processes. With the development of computer computation ability, computational fluid dynamics (CFD) method has been widely adopted and accepted to investigate hydrodynamics of complex two-phase flows. in the recent years. Since industrial applicants generally require us to consider additional physical processes, a two-fluid model in the Eulerian-Eulerian framework has been adopted for the turbulent bubbly flows with heat and mass transfer.

Considering the different characteristics of bubbly flows in vertical pipes and bubble columns, this dissertation involves the numerical simulations of bubby flows in vertical pipes and bubble columns, respectively. For the bubble flow containing different physical phenomena, break-up and coalescence of bubbles, boiling and CO2 absorption, we have proposed corresponding mathematical models and validated its reliability by comparing with published experimental data.

Considering the advantages of large eddy simulation (LES), which can capture the instantaneous behaviours of eddies, we mainly focus on the LES of bubbly flows, and the modified SGS model proposed by Long et al. (2020) is incorporated into our modelling to take the effect of the interaction between entrained bubbles and eddies with a similar turbulence length scale to the sub-grid scale into account. For a comparison purpose, k-ε model is employed to perform the simulations of bubbly flows. To achieve the accurate prediction, we also investigated grid generation scheme, the effect of interphase forces, and the models of interfacial heat and mass.

Overall, the results of this work give a reference to the numerical modelling of bubbly flows with heat and mass transfer, and expended the application range of LES, while the present approaches are partially successful and still need further development.

Date of Award	15 Jul 2025
Original language	English
Awarding Institution	University of Nottingham
Supervisor	Xiaogang Yang (Supervisor) & Guang Li (Supervisor)