Scientists Create Dry Sand Bubbles

_{Image: Alex Penn/ETH Zurich}

Scientists have demonstrated the ability of lighter particles (blue in the above picture) of sand to rise up through heavier sand particles (white in the above picture) in 'granulated bubbles' and 'fingers' with the application of an upward gas flow and vertical vibration. According to the team, this is the first time Rayleigh–Taylor (RT) instability has been shown in the flow of dry granular mixtures, such as sand.

RT instability is caused when two immiscible fluids of different densities interact, resulting in the less dense fluid pushing the heavier fluid out of the way as they separate. The team's discovery of the phenomenon could have far-reaching consequences, such as helping to model the physics behind lava flows, avalanches, and mudslides.

According to Professor Chris Boyce, a member of the team, "Our findings could not only explain geological formations and processes that underlie mineral deposits, but could also be used in powder-processing technologies in the energy, construction, and pharmaceuticals industries." Also stating, "We are especially excited about the potential impact of our findings on the geological sciences—these instabilities can help us understand how structures have formed over the long history of the Earth and predict how others may form in the future."

Read more: Columbia University