Grain flow is the movement of granular materials, such as sand, gravel, and soil, under the influence of gravity. It is a common phenomenon in nature, and it can be both destructive and beneficial. For example, grain flows can cause landslides and avalanches, but they can also be used to transport materials for construction and agriculture.
The shape of particles plays an important role in controlling grain flow. Angular particles, such as those found in crushed rock, tend to interlock with each other, which makes them more resistant to flow. Rounded particles, such as those found in beach sand, tend to flow more easily.
The researchers conducted a series of experiments to measure the flow rates of different types of granular materials. They found that the flow rate of a granular material is proportional to the square of the particle size and inversely proportional to the square root of the particle angularity.
This new understanding of how particle shape controls grain flow could help engineers manage coastal erosion and other natural hazards. For example, engineers could use angular particles to create barriers that slow down or stop grain flows. They could also use rounded particles to create surfaces that are more resistant to erosion.
The researchers' findings were published in the journal Physical Review Letters.
"Our work provides a new way to understand and control grain flow," said Professor Jessica Zhang, who led the research team. "This could have a significant impact on our ability to manage coastal erosion and other natural hazards."
