The three videos show an experiment in a Hele-Shaw cell where the upslope migration of a buoyant current of water (dark) is arrested by convective dissolution into the ambient propylene glycol (light). As described in the Appendix, the Hele-Shaw cell is 5.2cm tall with a 1.4mm gap between the plates, and the cell is tilted about 2.5 degrees counterclockwise relative to horizontal, as auxiliary material of the paper:
Buoyant currents arrested by convective dissolution.
C. W. MacMinn and R. Juanes, Geophysical Research Letters, 40(10):2017-2022 (2013), doi:10.1002/grl.50473.
** The videos play back about 30 minutes of realtime in about 23 seconds. The speedup factor of the videos over realtime changes once near the 4 second mark, increasing from about 15x to about 75x. **
In the first video, we show snapshots of the experiment in grayscale.
In the second video, we overlay our surface-growth model for the fingered front [cyan line] onto the snapshots from the first video. This simple growth model provides an excellent approximation to the evolution of the fingered front position.
In the third video, we overlay the actual fingered front (red points) and the paths of the fingertips (blue lines) from image processing onto the snapshots from the first video. We measure the depth of the fingered front at each horizontal position (red points) as the depth where the intensity of the image becomes smaller than a threshold value. We identify the fingertips as local minima of the fingered front. The paths of the fingertips illustrate the coarsening of the fingering pattern as the fingers grow and merge.