Photochromic flow visualization in single-phase and two-phase flows

A photochromic flow visualization technique that was originally introduced by Popovich and Hummel permits qualitative and quantitative velocity information to be obtained in a variety of complex flow situations. Examples of flow visualization studies include drop and bubble formation, distortion of flow fields caused by velocity probes, and others. While qualitative information on flow velocities can be obtained with relative ease, quantitative information cannot be extracted as readily and requires a modification of the visualization technique or use of an iterative evaluation method.