Bubble columns: flow transitions in the presence of trace contaminants

Observations are reported on the two-phase bubble flow of air rising through a stationary water phase. Distinctly different results have been measured for tap water and for distilled water. The difference in these results is attributed to the presence of an extremely small quantity of an unknown surface-active contaminant. Both the nature and the axial distribution of the contaminant are shown to be important in determining the ultimate flow regime.