Shapes and paths of an air bubble rising in quiescent liquids

TL;DR

This study experimentally and numerically investigates the shapes and paths of rising air bubbles in quiescent liquids across a wide range of physical parameters, providing a comprehensive phase plot of bubble behavior.

Contribution

First experimental phase plot of bubble behavior in quiescent liquids over extensive Galilei and Eotvos number ranges, validated by direct numerical simulations.

Findings

Distinct regimes of bubble behavior identified

Excellent agreement between experiments and simulations

Comprehensive phase plot presented for the first time

Abstract

Shapes and paths of an air bubble rising inside a liquid are investigated experimentally. About three hundred experiments are conducted in order to generate a phase plot in the Galilei and Eotvos numbers plane, which separates distinct regimes in terms of bubble behaviour. A wide range of the Galilei and Eotvos numbers are obtained by using aqueous glycerol solutions of different concentrations as the surrounding fluid, and by varying the bubble size. The dynamics is investigated in terms of shapes, topological changes and trajectories of the bubbles. Direct numerical simulations are conducted to study the bubble dynamics, which show excellent agreement with the experiments. To the best of our knowledge, this is the first time an experimentally obtained phase plot showing the distinct behaviour of an air bubble rising in a quiescent medium is reported for such a large range of Galilei and Eotvos numbers.