It is difficult for scientists to understand the behavior of innumerable moving particles and we are still learning new things about materials, such as sand, as shown by some of our past stories. In a new experiment, scientists observed two types of interacting sands, where one sand formed bubbles in another sand. Better understanding of the movements of these granular materials can lead to important results.
"There are many different motivating factors" to study how two sands move one after another, authored by Christopher Boyce, associate professor at the Columbia University Chemical Industry Department. – said Gizmodo. This includes construction, pharmaceuticals and even alternative energy.
Experiment consisted of a pair of sands, white "heavy" sand on black "light" sand, in a transparent rectangle. The black sand had a bit more, but lighter than grain, white sand. The machine shook the rectangle up and down, and the air goes up through the sand. The researchers observed how the granular "bubbles" and "fingers", made up of lighter black sand, leaked up through heavy white grains. National Academy of Sciences. This is the behavior that occurs when light liquids are pushed into a heavy fluid. These instabilities are formed when you put water on the surface of oil, for example.
Except for two sands – not water and oil, – explained Boyce. , which makes research interesting – water and oil do not like to mix, but these sands otherwise do not interfere with mixing. In this case, the computational modeling has shown that the gas flowing predominantly through lighter particles, and in combination with vibrations, begins to push out in the form of a wave-shaped form. The ascending forces of gas and light particles in combination with the force that coincides with the heavier sand lead to the fact that these waves turn into fingers, and then compressed into bubbles. And these were bubbles of sand, not of gas;
Scientists carefully monitored the jet to prevent the formation of gas bubbles
It seems simple, but it's the first time bubbles are on the border between granular solids, said Boyce. Sounds like a very specific installation that will not be present in the real world, the gases emitted by a couple of different granular materials can be used in industrial conditions to mix chemicals intended to interact with one another. Boyce said:
The team will continue to study what kinds of rare behavior also appear in granular solids. In the end, when scientists find new behaviors, they are often followed by new ways of using them.