Transverse acoustic spin and torque from pure spinning of objects

Abstract
Acoustic spin has been recently explored for many applications. In particular, transverse acoustic spin was demonstrated for inhomogeneous acoustic fields. In this Letter, we show the emergence of acoustic spin and torque in rotating acoustic objects of the same physical properties as the surrounding, to single out the effects purely due to rotation. The spinning of a cylindrical column of air or water in the same medium possesses intrinsic spin angular momentum, and we study the torque and force it experiences in evanescent acoustic fields. The resulting discontinuity can thus scatter sound in unusual ways, including a negative radiation force, although it has no imaginary part in its parameters.

Citation
Farhat, M., Chen, P.-Y., Amin, M., Alù, A., & Wu, Y. (2021). Transverse acoustic spin and torque from pure spinning of objects. Physical Review B, 104(6). doi:10.1103/physrevb.104.l060104

Acknowledgements
The research reported in this Letter was funded by King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under Grants No. OSR-2016-CRG5-2950 and No. OSR-2020-CRG9-4374, as well as KAUST Baseline Research Fund BAS/1/1626-01-01. A.A. acknowledges the support of the Simons Foundation and the Air Force Office of Scientific Research MURI program.

Publisher
American Physical Society (APS)

Journal
Physical Review B

DOI
10.1103/physrevb.104.l060104

Additional Links
https://link.aps.org/doi/10.1103/PhysRevB.104.L060104

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