Air bubble break-ups by vertical oscillations in micro- and normal gravity environments

Dynamics of a bubble subjected to vertical oscillations is studied experimentally in micro- and normal gravity environments. A large air bubble (typically $D=1.8$ cm in volume equivalent diameter) is sealed with a surrounding liquid in a cell oscillating vertically. The bubble breaks up when the acceleration of the cell exceeds a certain value $a_{cr}$. This critical acceleration $a_{cr}$ is substantially smaller in micro-gravity environment than in normal gravity environment. In both environments, $a_{cr}$ is found to be constant for a given surrounding liquid when the cell's oscillation amplitude $A$ is large in comparison with the bubble size $D$. It is also found that $ a_{cr}$ increases rapidly with decreasing $A$ below the bubble size $D$. Influence of surrounding liquid viscosity is investigated by experiments with surrounding liquids of different viscosities. An increase of kinematic viscosity by a factor $10^2$ (from 1 cSt to 100 cSt) is found to lead a 2-2.5 times larger critical acceleration in both environments. Experimentally obtained critical accelerations are discussed, being compared with a simple model based on hydrodynamic instability of an accelerated interface.