Avalanches on a Conical Bead Pile

Henry Whyte

2021

Avalanches are one of the most destructive forces in nature, a dangerous natural phenomenon that pose a risk to snowboarders, skiers and winter outdoor enthusiasts. Under the right environmental conditions, an avalanche can tear trees from its roots, flatten buildings, and consume anything before it, leaving a trail of destruction. At the College of Wooster with the help of a conical pile of steel-shot beads we can now investigate the conditions that may contribute to avalanches. The pile is driven through the autonomous dropping of beads onto the apex one at a time. Environmental conditions that facilitate an avalanche may change with time. Similarly, conditions in the lab change, which can effect the bead pile and subsequently experimental outcomes. The previous steel-shot beads used for this experiment were replaced this year with new beads of the same kind. To ensure the use of these new beads were not drastically changing the results of the experiment, an investigation of the mass data was completed. This investigation included comparing sets of data from the old beads and the new ones. Two runs were completed at different iii iv cohesion levels, where cohesion between the beads on the pile was created using the magnetic field due to a set of Helmholtz coils. From the probability distribution of avalanche sizes, I suggest that the amount of oil used to cover the older beads is greater than the amount on the newer set of beads. We also examined the use of video analysis and the software program PIVlab, which is used to analyze our avalanche videos. This program determines the velocity of small areas of the pile, and the magnitude of this velocity data was compared to that of a program called Tracker. Tracker is another video analysis tool which is well suited to track single particles, whereas PIVlab is better suited for analyzing the motion of whole systems. We found that the average velocity output from PIVlab was of the same order of magnitude as the calculated velocity from Tracker, which provides reassurance of our past and continued use of PIVlab.