20. Numerical Simulation of a Downward Two-Phase Vertical Flow: A Preliminary Analysis of Convection Intensity and Gas Flow Rate Effects

In the context of research on turbulent multiphase flows, the experimental and numerical reports available in the literature on downward bubble columns are still relatively scarce. Substantial advances in multiphase models, turbulence models, and new constitutive proposals for interfacial forces prove that the line of research is active and requires more scientific investigation. In this line, the current work aims to carry out a preliminary numerical analysis of a downward bubble column in a vertical tube with the ANSYS Fluent commercial package. A vertical pipe comprises the geometry used in the numerical experiment with a 20mm inner diameter. The multiphase flow is characterized by two average bubble diameters, 1.75 and 2.2 mm, and a gas volume fraction ranging from 2 to 10\(\%\) at the inlet. Regarding the analysis, initially, the convective intensity was varied to establish its influence on the axial velocity profile of the continuous phase and the void fraction distribution in the radial direction. At last, the gas flow rate was gradually increased to observe its effects on the radial void distribution. The results achieved were validated by comparison with well-established experimental data and presented satisfactory agreement in general.