Overlapping of acoustic bandgaps using fractal geometries

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

doi:10.1209/0295-5075/92/24007

Cited by 18 publications

(23 citation statements)

References 21 publications

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“…where ∂Ω i is the boundary of the i-th scatterer, k 0 is the wave number in the host medium, k c (ω) and Z c (ω) are the propagation constant and the impedance of the absorbing material of the scatterer i. By applying the boundary condition (13) in Γ i , we can obtain a simple relation between coefficients X i n and Y i n :…”

Section: Scattering Problem: Multiple Scattering Theory (Mst)mentioning

confidence: 99%

Tunable wideband bandstop acoustic filter based on two-dimensional multiphysical phenomena periodic systems

Romero‐García

Sánchez‐Pérez

Garcı́a-Raffi

2011

Journal of Applied Physics

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Abstract. The physical properties of a periodic distribution of absorbent resonators is used in this work to design a tunable wideband bandstop acoustic filter. Analytical and numerical simulations as well as experimental validations show that the control of the resonances and the absorption of the scatterers along with their periodic arrangement in air introduces high technological possibilities to control noise. Sound manipulation is perhaps the most obvious application of the structures presented in this work. We apply this methodology to develop a device as an alternative to the conventional acoustic barriers with several properties from the acoustical point of view but also with additional aesthetic and constructive characteristics.

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Section: Scattering Problem: Multiple Scattering Theory (Mst)mentioning

confidence: 99%

Tunable wideband bandstop acoustic filter based on two-dimensional multiphysical phenomena periodic systems

Romero‐García

Sánchez‐Pérez

Garcı́a-Raffi

2011

Journal of Applied Physics

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“…Ultra-thin meta-diffusers have also been designed showing very good performance at low frequencies [22,23]. Locally resonant materials have been also used for the mitigation of sound for traffic and railway noise showing their efficiency at low frequencies [15,[24][25][26][27][28][29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

Sound Absorption and Diffusion by 2D Arrays of Helmholtz Resonators

et al. 2020

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We report a theoretical and experimental study of an array of Helmholtz resonators optimized to achieve both efficient sound absorption and diffusion. The analysis starts with a simplified 1D model where the plane wave approximation is used to design an array of resonators showing perfect absorption for a targeted range of frequencies. The absorption is optimized by tuning the geometry of the resonators, i.e., by tuning the viscothermal losses of each element. Experiments with the 1D array were performed in an impedance tube. The designed system is extended to 2D by periodically replicating the 1D array. The 2D system has been numerically modeled and experimentally tested in an anechoic chamber. It preserves the absorption properties of the 1D system and introduces efficient diffusion at higher frequencies due to the joint effect of resonances and multiple scattering inside the discrete 2D structure. The combined effect of sound absorption at low frequencies and sound diffusion at higher frequencies, may play a relevant role in the design of noise reduction systems for different applications.

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“…Lubniewski and Stepnowski [6] developed a simple method to identify the seabed using elements of fractal analysis. Castiñeira-Ibáñez et al [7,8] presented an acoustic barrier to control the noise formed by rigid cylinders in the fractal geometry of a Sierpinski triangle. These structures are capable of producing sharp attenuation by means of destructive interference, as well as focalization through constructive interference.…”

Section: Introductionmentioning

confidence: 99%

Polyadic Cantor Fractals: Characterization, Generation, and Application as Ultrasonic Lenses

Castiñeira-Ibáñez¹,

Tarrazó-Serrano²,

Fuster³

et al. 2017

Fractal Analysis - Applications in Health Sciences and Social Sciences

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The term fractal was coined in 1975 by Benoit Mandelbrot. Since then, fractal structures have been widely used by the international scientific community. Its range of applications includes multiple areas, such as optics, physics, cryptography, medicine, economics, and so on. The application of fractal structures to modulate light beams in the field of optics has been extensively studied, and it has been shown that in some cases these new fractal lenses improve the response of traditional lenses. Fractal lenses are able to provide beamforming capabilities, and allow the optimization of the optical beam according to the specific requirements. In some applications, it may be necessary to improve the focus in a certain area, while in others it may be critical to obtain a sharp attenuation by means of destructive interference. It may even be required a beam profile with multiple focus and a certain control over them. This work investigates the application of fractal structures based on Polyadic Cantor sets as ultrasonic lenses, analyzing how the relation between the different design parameters and the performance of the lens. It is shown that the working frequency becomes a precise control mechanism that can modify dynamically the focus position of the lens.

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Overlapping of acoustic bandgaps using fractal geometries

Cited by 18 publications

References 21 publications

Tunable wideband bandstop acoustic filter based on two-dimensional multiphysical phenomena periodic systems

Tunable wideband bandstop acoustic filter based on two-dimensional multiphysical phenomena periodic systems

Sound Absorption and Diffusion by 2D Arrays of Helmholtz Resonators

Polyadic Cantor Fractals: Characterization, Generation, and Application as Ultrasonic Lenses

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