MSU physicists propose a way to “control” the speed of sound in a metamaterial 13:09

Russian physicists have proposed a way to create metamaterials with an artificially tuned speed of sound. This was reported by the press service of Moscow State University.

Modern physicists distinguish phonons, which are “imaginary” particles that transmit the energy of oscillatory motion, including sound. There are also phononic crystals that allow you to control the properties of the sound passing through it.

Now MSU experts have come up with the concept of a two-dimensional photonic crystal and calculated its acoustic properties. Thus, in the considered isotropic crystal of molten quartz, periodically repeating round holes are placed. The authors calculated the main acoustic properties: the speed of sound and polarization, as well as the direction of propagation of the energy of all waves propagating in the material.

It turns out that the value of acoustic anisotropy, which occurs when inhomogeneities appear, is determined by the geometry of the holes – the ratio of the diameter to the period of the unit cell. As it turned out, the choice of different geometry allows you to change the main acoustic parameters of the environment according to needs. Thanks to this, it becomes possible to control the properties of sound in a wide range, changing not only its direction, but also its propagation speed.

“Such phononic crystals meet the requirements for creating acoustic-optical devices based on them: filters, deflectors and modulators, where it is necessary to have a certain sound speed,” said Natalia Polikarpova, one of the authors of the study.

An article describing this work published in Materials magazine.

Earlier astronomers suggested Description of the “maneuvers” of the interstellar asteroid Oumuamua.



Source: Gazeta

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