A team of researchers managed to identify the 'bubbles' that are formed by mixing two types of sand, material that tends to join, and subject them to a vertical vibration and a rising gas flow. The result was a behavior similar to that of liquids, published Proceeding of the National Academy of Sciences.
To carry out this experiment, the chemical engineer from Columbia University, Chris Boyce, worked with specialists from the Federal Polytechnic School of Zurich. They used computational and experimental models to mix two types of sand, one lighter than the other, and they found that the lighter grains rose and formed a kind of 'fingers' Y 'granular bubbles'.
As they explained, the behavior of the ascending gas flow, through the granular material, was similar to the instability of Rayleigh-Taylorn (RT), when Two fluids of different density join and the lighter pushes on the heavier one, as the oil does when rising above the water. However, this phenomenon, until now, had not been observed in dry granular elements.
"We think it's a transformative discovery," Boyce said, adding that they found "a granular analog of one of the latest mechanical fluid instabilities." In addition, he stressed that while "the analogues of other important instabilities" were discovered in "granular flows in the last decades", the RT instability had "eluded a direct comparison".
For the chemical engineer, this discovery "could not only explain the geological formations and the processes that underlie mineral deposits, but could also be used in dust processing technologies in the energy, construction and pharmaceutical industries. "
Finally, he said that these "instabilities can help to understand how structures were formed throughout the history of the Earth and predict how others can be formed in the future."
If you liked it, share it with your friends!