How does the flow structure of a gradually contaminating bubble evolve

The behavior of a rising bubble is greatly affected by a small amount of surfactant. It is explained by the Marangoni effect, which is caused by the concentration gradient of surfactant at the interface. The Marangoni effect changes the boundary conditions and the flow structure around the bubble. Experiments were conducted using polarization measurement techniques to capture changes in flow structure. For example, for a bubble rising in a Triton X-100 solution, which is difficult to desorb, the boundary conditions transitioned from the back of the bubble as if it were solid. In contrast, the front of the bubble remained a clean bubble. The results presented should provide a fundamental understanding of the various dynamics of bubbles rising in a surfactant.