Viscothermal Losses in Double-Negative Acoustic Metamaterials

Abstract

The influence of losses in double-negative metamaterial slabs recently introduced by Graciá-Salgado et al. [Phys. Rev. B 88, 224305 (2013)] is comprehensively studied. Viscous and thermal losses are considered in the linearized Navier-Stokes equations with no flow. Despite the extremely low thicknesses of boundary layers associated with each type of losses, the double-negative behavior is totally suppressed for the rigid structures under analysis. In other words, almost 100% of the energy transmitted into the slab is dissipated by viscothermal effects, in agreement with experimental data. Simulations undertaken for larger structures, using scale factors of up to 20 times, show that double-negative behavior is never recovered. The huge dissipation obtained by these structures leads us to propose them as interesting alternatives to conventional absorbers for specific situations, e.g., when treating low frequencies or when the excitation is narrow banded.

Dark Solitons in Acoustic Transmission Line Metamaterials

“…Dissipation naturally plays a key role in such structures, especially in super-absorbing sound materials [21,22] (see also work in Refs. [23,24]). The combination of dispersion and dissipation [20,23,[25][26][27] has mainly been investigated in the linear regime; nevertheless, the additional effect of nonlinearity, which is naturally introduced at high acoustic levels has not been studied in detail in acoustic metamaterials.…”

Wave propagation in a nonlinear acoustic metamaterial beam considering third harmonic generation

“…Although there are significant differences between the numerical results and the UC solutions, their tendencies, jumping frequency and peaks of curves are consistent. The FE results verify the peak near ω r /3 and the valley at [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] Hz. For f F >30 Hz, h 3 gradually increases to a saturate value and features a highly efficient THG band in 35<f F <53 Hz.…”

Acoustic metasurfaces

“…Although these losses are well-known phenomena in acoustics, the influence of these losses on acoustic metamaterials and acoustic metasurfaces requires further investigation 56 . These losses can be accounted for numerically 57 or analytically 58 , and their influence on the performance of acoustic metasurfaces has been investigated 58 . Another effect found in acoustic systems is the acoustic-structure interaction, which occurs when sound impinges on the non-rigid boundary (or wall) of an acoustic metasurface 59 .…”