Study of Strong Pressure Wave Propagation in a Two-Phase Bubbly Mixture

A geometrically simple configuration of a gas bubble expanding in a bubbly medium is chosen to study multi-scale modeling approaches in simulating multiphase flows. Three solvers following the Eulerian-Lagrangian, multi-component compressible and analytical approaches have been studied for different bubbly medium void fractions. In the Eulerian-Lagrangian approach, an incompressible solver was coupled with a bubble dynamics model, while for the Eulerian two-fluid approach and the analytical model the surrounding fluid was assumed to be a homogeneous mixture. It was found that both two-fluid and analytical models match very well for the cases tested. The Eulerian-Lagrangian model shows that the dynamics of the bubbly medium and the expanding bubble are inherently coupled in a non-linear fashion. Presence of discrete bubbles also introduces localized perturbations in the void fraction as well as in the pressure distribution which cannot be captured by the homogeneous mixture models.