This video demonstrates that when particles are suspended in a fluid with a different density, they self-organize into eruptions of cohesive flocks. This was a research conducted by the team at UChicago that spans soft condensed matter, fluid dynamics, turbulence, and topological flow to understand the mechanisms that underpin many natural phenomena 1. They discovered that a spinner creates a localized three-dimensional region of vorticity, which they termed a “vortlet”, that drives the particle’s motion. The research to understand how these vortlets behave and interact helps understand what flow is made of, especially how collective flows emerge from lots of little active agents (such as active nematics, rollers, and spinners). This article was a good summary of the research: A new spin on flow dynamics — Go with the Flow!
Footnotes
-
Chen, P., Weady, S., Atis, S. et al. Self-propulsion, flocking and chiral active phases from particles spinning at intermediate Reynolds numbers. Nat. Phys. (2024) ↩