Abstract
Mixing of liquid caused by an air bubble with zigzag or spiral motion in a still liquid in a pipe is investigated experimentally using a photochromic dye. A part of the liquid is activated by UV light and subjected to the liquid motion caused by a rising bubble of Re=209. The visualized mixing patterns showed that the dye is mixed by vortex motions in the bubble wake for both motions. The concentration distributions were deduced from the dye images using Lambert-Beer's law and the mass dispersion of liquid was evaluated. The some bubbles with spiral motion caused stronger mixing than the bubbles with zigzag motion.
