Transmission and rainbow trapping of acoustic waves in a fluid medium using gradient-index superlattices

Recently, rainbow trapping of acoustic/elastic waves in gradient artificial structures has shown promising applications in energy harvesting and frequency separation. However, the novel phenomenon of acoustic superlattices for underwater acoustic waves has not been explored. In this work, we establi...

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Veröffentlicht in:Journal of applied physics 2021-04, Vol.129 (15)
Hauptverfasser: Xu, Bai-qiang, Wu, Jiao, Lu, Wei, Gu, Xin, Zhang, Li-juan, Zhang, Sai, Zhang, Yu
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Sprache:eng
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Zusammenfassung:Recently, rainbow trapping of acoustic/elastic waves in gradient artificial structures has shown promising applications in energy harvesting and frequency separation. However, the novel phenomenon of acoustic superlattices for underwater acoustic waves has not been explored. In this work, we establish the theoretical model of underwater acoustic waves propagating through the gradient-index superlattice (GISL) by using the transfer matrix method. We show that the combined band structures of infinite sub-superlattices and the transmission curves of finite GISL exhibit Bragg forbidden bands that are wider than those of periodic ones, which implies the occurrence of rainbow trapping. On this basis, the effects of gradient factor, period number, and water thickness are discussed, and the tunability of the trapping range is also explained. Furthermore, simulations with Gaussian beam incidence are performed through finite element methods. The results in frequency-domain and time-domain both indicate perfect performances of energy localization and frequency separation for acoustic waves of different frequencies. Our findings show possibilities for the design of underwater acoustic devices, such as acoustic sensors and frequency dividers.
ISSN:0021-8979
1089-7550
DOI:10.1063/5.0040507