Granular materials, such as sand, gravel, and rice, are all around us. They are used in everything from construction to food production. But despite their ubiquity, we still don't fully understand how they behave.

One of the most interesting properties of granular materials is their ability to self-organize. When a granular material is poured into a container, it will eventually settle into a stable configuration. This configuration is often characterized by the formation of arches and vaults, which help to support the weight of the material.

How do granular materials manage to form these structures? A new study from researchers at the University of Amsterdam provides some insight. The study, which was published in the journal Nature Physics, shows that granular materials are able to self-organize by using a process called granular convection.

Granular convection is a process in which heat is transferred through a granular material by the movement of its particles. When a granular material is heated, the particles at the bottom of the container will become warmer than the particles at the top. This difference in temperature causes the particles at the bottom to rise, while the particles at the top fall. This movement of particles creates a convective flow that helps to distribute heat throughout the material.

The researchers found that granular convection can also help to self-organize granular materials. When a granular material is heated, the convective flow will cause the particles to move around and rearrange themselves. This rearrangement can lead to the formation of arches and vaults, which help to support the weight of the material.

The researchers' findings could have important implications for the design of structures that use granular materials. By understanding how granular materials self-organize, engineers could design structures that are more stable and less likely to collapse.

How granular materials get themselves out of a jam

When a granular material is confined, such as in a silo or a hopper, it can become jammed. This happens when the particles are so tightly packed together that they can no longer move. Jamming can cause problems in industrial settings, such as when it prevents materials from flowing out of a silo.

The researchers found that granular convection can also help to relieve jamming. When a granular material is heated, the convective flow will cause the particles to move around and rearrange themselves. This rearrangement can lead to the formation of channels and pathways that allow the material to flow.

The researchers' findings could have important implications for the design of industrial equipment that handles granular materials. By understanding how granular materials get themselves out of a jam, engineers could design equipment that is less likely to jam and more efficient.