Always spectacular to watch the magical billowing revealed by the schlieren imaging technique. As in the last investigation the images below are of dense cold water descending from an ice cube in room temperature water. While we dont normally see this magical cascade of water within water the schlieren imaging technique allows this ‘invisible’ phenomena to be seen. Schlieren uses a set of mirrors to control the light and make the invisible visible. Differences in water temperature/density cause the light to bend and dissrupt a uniform color gradient, which allows the intricate patterns to be photographed.
This is a followup to the last investigation. This time I used some small circular plates of ice, and some larger ones (you can see one held in the field of view). The field of view is approximately 4″ in diameter for these images.
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These images were taken using a schlieren system. A point source of light is collimated by a parabolic mirror and passed through the test region. Density gradients in the test region cause changing indices of refraction which causes bending of the collimated light. A second parabolic mirror is used to refocus the beam onto a knife blade (in this case a color bulls-eye filter). The knife blocks some of the light so that some bent rays of light are blocked. The result is a black and white image with light and dark areas in the areas where the density is changing. A color bulls-eye filter was used in place of the knife blade to create these color images. Instead of blocking the light the filter re-colors the bent light rays to indicate the magnitude and or direction of the fluid’s changing temperature/density. The equipment was borrowed from the University of Colorado at Boulder for the Mechanical Engineering course Flow Visualization.
For more information on my setup or this phenomenon, please ask and I’ll tell you; or rather, let you know what I have found in my research.