Abstract
Flow visualization technique using a photochromic dye was applied to investigate the wake vortices behind a rising bubble in a still liquid. A spiropyran dye TMINBP was dissolved in a kerosene-paraffin mixture and the solution was activated by UV-LED projectors. The activated dark blue liquid was subjected to the fluid motion caused by a zigzag rising bubble of which Reynolds number is 255. A hairpin vortex loop shed from a bubble was clearly visualized. A stereo display system was constructed using a commercial stereo display and used to examine the complex three-dimensional vortices in the bubble wake. The concentration distributions of activated dye were deduced from the visualized images using Photochromic Concentration Measuring (PCM) technique. These concentration distributions can be used to evaluate the liquid mass mixing quantitatively. A water-soluble triarylmethane dye 'Acid Violet 19' was also applied to visualize the wake vortices behind an air bubble in water.
