The authors conducted experiments on different liquids.
Physicists have learned to control the drops of a liquid using ultrasound. In the new experiments, they not only forced them to levitate in the air, but turned flat drop in bubble with air inside. The results were published in the journal Nature Communications.
Despite the fact that blowing bubbles is considered entertainment for kids, this phenomenon plays an important role in many technological processes. In particular, their education plays an important role in the production of food, medicines, cosmetics and ultralight materials.
A few years ago, physicists have demonstrated acoustic levitation, that is, the retention and movement of small bodies in the air using the pressure of sound waves. In the new work, scientists from China, Britain and Australia have learned to bend the drops in the air, creating a hollow bubbles.
The authors conducted experiments on a variety of liquids, including water. First, the increase in sound intensity transforms a drop into a concave surface. Then the acoustic waves begin to resonate within her, forcing the walls to expand until they impinge on the formation of the bubble.
The resulting bubbles were very stable, their lifetime is measured in tens of minutes. The fact that usually similar formation burst, as gravity attracts the substance to the underside of the bubble and on the top it becomes too thin.
However, the effect of sound waves inhibits the flow of liquid, whereby bubbles do not collapse much longer. The authors hope that their study will find application in the manufacture of materials in which a drop of one liquid must be surrounded by a layer of another.
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