Evanescent waves and deaf bands in sonic crystals

Romero‐García, Vicente; Garcı́a-Raffi, L. M.; Sánchez‐Pérez, J. V.

doi:10.1063/1.3675801

Cited by 26 publications

(11 citation statements)

References 30 publications

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“…However, extending the domain to complex Bloch wave-vectors, one could, e.g., visualize the evanescent behavior at frequency intervals marking a band gap. 34,35 For the sake of simplicity we have constructed cylinders with circular perforations and used glass wool to make porous cores. However, other core materials as well as shell perforations could be modeled if suitable impedance expressions are at hand, see, e.g., Ref.…”

Section: Discussionmentioning

confidence: 99%

Scattering by an array of perforated cylinders with a porous core

Forssén

2014

The Journal of the Acoustical Society of America

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In this work multiple scattering by an array of perforated cylindrical shells with a porous core has been investigated. A semi-analytical model to predict scattering from such cylindrical units is presented in the context of the multiple scattering theory (MST), and validated against laboratory experiments. The suggested semi-analytical multiple scattering model uses an impedance expression to include the perforated shell in the scattering coefficients, which is a compact way to describe a composite scatterer in MST. Calculation results of a small array are shown to be in excellent agreement with measured data. Predictions and data show that perforated cylinders with empty cavities exhibit a strong and narrow insertion loss peak at resonance, though simultaneously suffer from amplification below resonance. By adding porous material in the core of the scatterer adverse effects below the resonance peak were suppressed. In addition, it was found that the reduction peak broadens, though at a cost of a reduced peak amplitude. Finally, it has been shown that adding porous material in a perforated shell will introduce partial absorption of the incoming field, which can be optimized by adjusting the perforation ratio of the shell.

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Section: Discussionmentioning

confidence: 99%

Scattering by an array of perforated cylinders with a porous core

Forssén

2014

The Journal of the Acoustical Society of America

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“…Years after the exhibition of Eusebio Sempere's sculpture in Madrid in 1995, which is recognized as the first experimental work on noise attenuation from a periodic structure [19], the scientific community discovered how sonic crystals could actually be used to reduce noise pollution and research on the application of 2-D sonic crystals has increased considerably [20][21][22].…”

Section: Sonic Crystals As Acoustic Barriersmentioning

confidence: 99%

Recent Developments in Sonic Crystals as Barriers for Road Traffic Noise Mitigation

2019

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Noise barriers are the most widespread solution to mitigate noise produced by the continuous growth of vehicular traffic, thus reducing the large number of people exposed to it and avoiding unpleasant effects on health. However, conventional noise barriers present the well-known issues related to the diffraction at the edges which reduces the net insertion loss, to the reflection of sound energy in the opposite direction, and to the complaints of citizens due to the reduction of field of view, natural light, and air flow. In order to avoid these shortcomings and maximize noise abatement, recent research has moved toward the development of sonic crystals as noise barriers. A previous review found in the literature was focused on the theoretical aspects of the propagation of sound through crystals. The present work on the other hand reviews the latest studies concerning the practical application of sonic crystal as noise barriers, especially for road traffic noise mitigation. The paper explores and compares the latest developments reported in the scientific literature, focused on integrating Bragg’s law properties with other mitigation effects such as hollow scatterers, wooden or recycled materials, or porous coating. These solutions could increase the insertion loss and frequency band gap, while inserting the noise mitigation action in a green and circular economy. The pros and cons of sonic crystal barriers will also be discussed, with the aim of finding the best solution that is actually viable, as well as stimulating future research on the aspects requiring improvement.

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“…. Considering a symmetric structure with respect to y = L s /2 excited by a plane wave along the x-axis ensures that K m y = 0, ∀m ∈ M [21]. Therefore, the two dimensional LT reduces to…”

Section: Slatcowmentioning

confidence: 99%

Complex Dispersion Relation Recovery from 2D Periodic Resonant Systems of Finite Size

2019

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The complex dispersion relations along the main symmetry directions of two-dimensional finite size periodic arrangements of resonant or non-resonant scatterers are recovered by using an extension of the SLaTCoW (Spatial LAplace Transform for COmplex Wavenumber) method. This method relies on the analysis of the spatial Laplace transform instead of the usual spatial Fourier transform of the measured wavefield in the frequency domain. We apply this method to finite dimension square periodic arrangements of both rigid and resonant scatterers embedded in air, i.e., to finite size sonic crystals and finite size acoustic metamaterials, respectively. The main hypothesis considered in this work is the mirror symmetry of the finite structure with respect to its median axis along the analyzed direction. However, we show that the method is robust enough to provide excellent results even if this hypothesis is not fully satisfied. Effectively, a minor asymmetry could be considered as a side effect when the structure is large enough because Laplace transforming the field along the main symmetry directions also implies averaging the field in the perpendicular one. The calculated complex dispersion relations are in excellent agreement with those obtained by an already validated technique, like the Extended Plane Wave Expansion (EPWE). The methodology employed in this work is intended to be directly used for the experimental characterization of real 2D periodic and resonant systems.

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Evanescent waves and deaf bands in sonic crystals

Cited by 26 publications

References 30 publications

Scattering by an array of perforated cylinders with a porous core

Scattering by an array of perforated cylinders with a porous core

Recent Developments in Sonic Crystals as Barriers for Road Traffic Noise Mitigation

Complex Dispersion Relation Recovery from 2D Periodic Resonant Systems of Finite Size

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