Shapes and paths of an air bubble rising in quiescent liquids

We investigate shapes and paths of an air bubble rising inside a liquid via experiments and direct numerical simulations. Close to three hundred experiments are conducted in order to generate a phase plot in the Gallilei and Eotvos numbers plane. The plot separates distinct regimes, in terms of bubble behavior; specifically, an axisymmetric, skirted, wobbling, and three types of break-up behaviors are observed in our experiments. A wide range of Gallilei and Eotvos numbers is obtained by using aqueous glycerol solutions of different concentrations as the surrounding fluid and by varying the bubble size. The dynamics of the bubbles in each regime is investigated in terms of shapes, topological changes and trajectories followed by the bubbles. The present study complement the numerical simulation results presented by Tripathi et al. (Nature Communications, 2015).