Cyclones and attractive streaming generated by acoustical vortices

What is it about?

In everyday life, we routinely observe the conversion of wind to sound, e.g. in wind instruments, airplanes turbofans or windmills. The reverse happens when very intense sounds get attenuated during their propagation. Here, we show that flows reminiscent of cyclones can be generated from specific acoustic fields called acoustical vortices. These vortical flows can be precisely tailored by adjusting the properties of the sound beam, which is made possible by advanced sound generation systems.

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Why is it important?

Hydrodynamic vortices play a fundamental role in many natural and industrial systems ranging from tornadoes and fish swimming, to planes and chemical mixers. Vorticity controllers based on sound might therefore help us reaching a better understanding of their underlying physics. But they might also opens new perspectives in areas such as microscale stirring technology, bio-inspired locomotion or complex flow control.