Quantitative comparison between volume-of-fluid and two-fluid models for two-phase flow simulation using OpenFOAM

This study compared numerical characteristics of volume-of-fluid (VOF) and two-fluid models for the two-phase flow simulation by using open-source computational fluid dynamics software (OpenFOAM). In both models, the pressure-implicit method for pressure-linked equations was solved to obtain transient pressure and velocity fields. For the simulation of subgrid-scale bubbles, the VOF model was coupled with a Lagrangian discrete bubble model (DBM). In the single bubble rising case, kinematic and dynamic parameters predicted by the two-fluid model were poor. However, in the bubbly flow case, this model predicted the gas and liquid velocities well and, similarly, the liquid front position in the free surface flow case. On the other hand, the VOF model was less accurate in describing bubbly flow, despite the inclusion of the DBM. While the two-fluid model is recommended for the simultaneous simulation of separated and dispersed flows, the VOF model is more effective for separated flows.