Non-reciprocal scattering in shear flow

Saverna, Charlotte; Aurégan, Yves; Pagneux, Vincent

doi:10.1121/1.5120523

Cited by 4 publications

(1 citation statement)

References 42 publications

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“…Total reflection for a particular combination of multiple travelling modes considered here is understood as a result of linear cancellation in transmission to the propagative channel(s) of the adjacent waveguide. It is noted that total reflection of a travelling acoustic mode or a mode-like wave can also occur owing to an acoustically hard wall, a resonator attached to a waveguide [44], the slowly varying cross-section of a duct that can support an acoustic turning point of the Wentze-Kramers-Brillouin (WKB) approximation where a slowly varying duct mode changes from cut-on to cut-off [45], the narrowing potential core of a jet flow [46] and a shear layer in flow [47][48][49].…”

Section: B Notes On Total Reflection Of Guided Waves and Trapped Modesmentioning

confidence: 99%

Total reflection of two guided waves for embedded trapped modes

Dai

2020

Preprint

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To investigate the mechanism of wave trapping, acoustic embedded trapped modes associated with two-resonant-mode interference in two-dimensional duct-cavity structures are calculated by the feedback-loop closure principle, which allows us to analyse the travelling modes that construct the trapped modes. The exact two coexisting resonant modes that underpin an embedded trapped mode in a cavity open to two semi-infinite ducts are numerically demonstrated. At the interface between the cavity segment and a duct, total reflection can occur for a particular combination of two propagative guided waves in the cavity. With a particular cavity length and a particular frequency, total reflection also happens for the two reflected waves at the opposite end of the cavity. In this way, the two coexisting standing waves underpin a trapped mode. It is found that the two standing waves are not two closed-cavity modes. Thus, this work presents a new understanding of such embedded trapped modes as a product of total reflection of two guided waves at the interface between two waveguides, rather than interference between two eigenmodes of a closed cavity. For quasi-trapped modes, the Fano scattering phenomenon owing to the effects of two acoustic channels is also shown.

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Section: B Notes On Total Reflection Of Guided Waves and Trapped Modesmentioning

confidence: 99%

Total reflection of two guided waves for embedded trapped modes

Dai

2020

Preprint

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Diffraction grating with space-time modulation

Pham

Maurel

2022

Journal of Computational Physics

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Asymmetric transmission and coherent perfect absorption in a periodic array of thermoacoustic cells

Olivier

Maddi

Poignand

et al. 2022

Journal of Applied Physics

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This paper describes some exotic scattering properties of a one-dimensional network of thermoacoustic cells and characterizes them experimentally. The considered two-port consists of a waveguide containing a periodic arrangement of porous materials subjected to temperature gradients and separated by empty sections. The interaction of an acoustic wave with the temperature gradients leads to an inherently nonreciprocal phenomenon known as the thermoacoustic effect. It is shown that this effect can be exploited for the design of systems with exotic acoustic scattering properties through two experimental demonstrations. The first example showcases a balanced asymmetric transmitter with transmission coefficients inverse of each other, yielding a nonreciprocity factor of 18 dB, without reflections. The second example shows a coherent perfect absorber, where maximum absorption is achieved for a wide range of temperature gradients by controlling the relative amplitudes and phasing of incoming waves.

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Non-reciprocal scattering in shear flow

Cited by 4 publications

References 42 publications

Total reflection of two guided waves for embedded trapped modes

Total reflection of two guided waves for embedded trapped modes

Diffraction grating with space-time modulation

Asymmetric transmission and coherent perfect absorption in a periodic array of thermoacoustic cells

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