In an experiment originally planned for the International Space Station, physicists at Duke University have devised a controlled, measurable method to make a container of granules -- in this case plastic beads -- "freeze" into the equivalent of a solid-state crystal, or "melt" into the equivalent of a fluid, by alternating the rates that the beads are stirred or shaken.
Results from these experiments also apply to other types of "granular materials," a term scientists use to describe aggregations of solid objects that, according to the circumstances, flow like liquids and gases or clump like solids, said Duke physics professor Robert Behringer, who has spent much of his career studying them. The research was funded by NASA.
"Our technique allows us to both control and measure the effect of different ways to energize a granular material, which has not been possible before," said Behringer, who with his postdoctoral researcher Karen Daniels described the work in a paper published April 29, 2005, in the journal Physical Review Letters.
Monte Basgall | EurekAlert!
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