Direct numerical simulations of bubble-particle interactions*

The interaction between a freely rising deformable bubble and a settling particle in a Newtonian background fluid is studied. The density and viscosity ratios between the bubble and the background fluid are kept constant at 10³  and 10², respectively. The study considers the effect of varying the bubble Bond number (Bo) and Galileo number (Ga) on the interaction. The simulations are implemented using three-dimensional particle-resolved DNS using Level Contour Reconstruction Method (LCRM); this is a hybrid level-set front-tracking method to accurately capture the motion and interaction of the bubble and particle. The transient numerical simulations show that the deformation of the bubble varies depending on whether the interaction is dominated by surface tension or gravitational forces. When the bubble approaches the particle, a thin film of liquid is trapped between the rising bubble and the settling particle and begins to drain. After drainage, the thin liquid film undergoes rupture forming a three-phase contact line. We present results of the spatio-temporal evolution of the bubble-particle interaction and the associated velocity, vorticity, and pressure fields of all three phases.