Depositional morphology of sedimentary particles. Increasing the injection volume or settling height increases the deposition radius.
Credit: M. Souzy et al., 2025
They used spherical borosilicate glass beads of various diameters to represent the salt particles and filled a cylindrical tube with a fixed amount of different beads. They then released the beads by sliding the bottom of the tube, and filmed them falling and settling with a Nikon D300 camera mounted at the top of the tank. The tank was illuminated from below by a uniform LED light screen and diffuser to provide a uniform background.
The physicists discovered that gravity pulls single particles to the bottom of the tank, creating a small wake resistance that affects the flow of water around them. The perturbation becomes even more complex when many large particles are ejected at once, each with its own wake that affects neighboring particles. Therefore, the falling particles start moving horizontally, and the falling particles are distributed in an expanding circular pattern.
Particles released from a lower height fall faster and form a pattern with a clean central area. Particles emitted from a higher height take longer to fall to the bottom, and the cloud of particles expands radially until the particles are far enough apart that they are no longer affected by the wakes of neighboring particles and no longer form a cloud. Masu. In that case, a homogeneous salt ring deposit is finally obtained.
“These are the key physical elements, and despite its apparent simplicity, this phenomenon involves a wide range of physical concepts, including deposition, non-creeping flow, long-range interactions between multiple bodies, and wake entrainment.” Contains. Susie said.. “Things get even more interesting when you find that larger particles are more radially shifted than smaller particles. This means that you can sort particles by size just by dropping them into a tank. Simple observations in everyday life Overall, it was a great experience because I quickly learned that there are a wide variety of hidden body mechanisms.”
According to the authors, these phenomena are relevant outside the kitchen as well, particularly in geophysical and industrial contexts such as “the discharge of dredged materials and industrial waste into rivers, lakes, and oceans.” The authors write that this is notable. “In scenarios involving contaminated waste, it is important to understand the behavior of both the solid waste and the interacting fluid.”
Physics of Fluids, 2025. DOI: 10.1063/5.0239386 (About DOI).
