All Mixed Up

If you fill a barrel part-way with red beads, add some green beads, and then roll it around the room a bit, will your beads blend? It depends on the properties of the two bead types, but conventional wisdom holds that wet beads will remain mixed more easily than dry ones. In a recently published research paper, a team of scientists shows that this thinking is not always correct. By mixing wet and dry beads in a tumbler, and developing a theory for interacting beads, they found the precise conditions that lead to mixing or separation. In some cases, simply adding water will cause two types of particles to separate. Their theory might suggest improved processing methods in many industries, from pharmaceutical manufacturing to fuel delivery in power plants.

A Sticky Distinction. Particles with differing surface properties will mix when rolled in a dry tumbler (left) but segregate when wet. A new theory predicts the conditions for each result.

Image Credit:  Phys. Rev. Lett., 90, 184301 (2003)

Read more about this research at Physical Review Focus.

Text courtesy of Physical Review Focus.