Supplemental Material: Plucking phenomena in nonuniform flow
journal contributionposted on 01.10.2018, 00:00 by Clare Wilkinson, David J. Harbor, Elliott Helgans, Joel P. Kuehner
Geosphere, October 2018, v. 14, p. 2157-2170, doi:10.1130/GES01623.1, Supplemental Movie F. Results of the particle image velocimetry (PIV) experiment. This video has been flipped from the original recording so that flow is shown conventionally, left to right, to match the data shown in Figure 5 of the manuscript. The first segment of the video shows the vertical sheet laser crossing the experimental flow during plucking the middle of three plaster blocks. In next two video segments, three panels show the PIV results with the video of the flow. The lower panel is the high-speed video. The middle panel shows clockwise vorticity (counterclockwise is black). The upper panel shows either instantaneous velocity direction and magnitude, or velocity difference (→V–→ Vavg), with color indicating absolute velocity magnitude in both. → V is the instantaneous velocity vector at a given location in the current vector image; → Vavg is the average velocity vector of any current vector image. Subtracting → V–→ Vavg provides the difference vector, which represents deviation from the mean. →V is a function of (x,y,t) and → Vavg is a function of (t). The time “t” is the moment of time represented by the current vector image. The final video segment is a repeat with a slower frame rate near the 2.4 s mark (2400 ms) when the middle block begins to lift at the upstream edge. This almost imperceptible movement is best observed by “scrubbing” or sliding the time bar of the video back and forth near 2400 ms.