A Benchmark Study on Eigenfrequencies of Fluid-Loaded Structures

Kronowetter, Felix; Baydoun, Suhaib Koji; Eser, Martin; Moheit, Lennart; Marburg, Steffen

doi:10.1142/s2591728520500139

Cited by 5 publications

(1 citation statement)

References 38 publications

(41 reference statements)

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“…In contrast, localized solutions in the continuum generally couple to open propagation channels, becoming leaky resonances. The eigenfrequency of the highly localized quasi-trapped modes is complex, in which the real part denotes the resonance frequency, and the imaginary part characterizes the radiation loss 13 , 14 . For a particular configuration of the geometric parameters, the radiation loss vanishes and the resonances become confined states.…”

Section: Introductionmentioning

confidence: 99%

Realistic prediction and engineering of high-Q modes to implement stable Fano resonances in acoustic devices

Kronowetter,

Maeder,

Chiang

et al. 2023

Nat Commun

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Quasi-bound states in the continuum (QBICs) coupling into the propagating spectrum manifest themselves as high-quality factor (Q) modes susceptible to perturbations. This poses a challenge in predicting stable Fano resonances for realistic applications. Besides, where and when the maximum field enhancement occurs in real acoustic devices remains elusive. In this work, we theoretically predict and experimentally demonstrate the existence of a Friedrich-Wintgen BIC in an open acoustic cavity. We provide direct evidence for a QBIC by mapping the pressure field inside the cavity using a Laser Doppler Vibrometer (LDV), which provides the missing field enhancement data. Furthermore, we design a symmetry-reduced BIC and achieve field enhancement by a factor of about three compared to the original cavity. LDV measurements are a promising technique for obtaining high-Q modes’ missing field enhancement data. The presented results facilitate the future applications of BICs in acoustics as high-intensity sound sources, filters, and sensors.

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Section: Introductionmentioning

confidence: 99%

Realistic prediction and engineering of high-Q modes to implement stable Fano resonances in acoustic devices

Kronowetter,

Maeder,

Chiang

et al. 2023

Nat Commun

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Sensitivity analysis of acoustic eigenfrequencies by using a boundary element method

Zheng

Zhao

Gao

et al. 2021

The Journal of the Acoustical Society of America

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This paper presents a boundary element-based scheme for the sensitivity analysis of acoustic eigenfrequencies of both interior and exterior acoustic systems. The nonlinear eigenvalue problem generated by the acoustic boundary element method is first reformulated into a generalized eigenvalue problem of reduced dimension through a contour integral approach. The sensitivity formulations for acoustic eigenfrequencies are then derived based on an adjoint method that uses both the right and left eigenvectors. The adaptive cross approximation in conjunction with the hierarchical matrices is used to reduce the solution burden of the boundary element systems. The Burton-Miller-type combined formulation is applied to shift the spurious eigenfrequencies and their sensitivities, and the strategies to identify the spurious results are suggested. Three numerical examples are used to verify the accuracy and applicability of the developed scheme.

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Sound attenuation enhancement of acoustic meta-atoms via coupling

Kronowetter,

Pretsch,

Chiang

et al. 2023

The Journal of the Acoustical Society of America

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Arrangements of acoustic meta-atoms, better known as acoustic metamaterials, are commonly applied in acoustic cloaking, for the attenuation of acoustic fields or for acoustic focusing. A precise design of single meta-atoms is required for these purposes. Understanding the details of their interaction allows improvement of the collective performance of the meta-atoms as a system, for example, in sound attenuation. Destructive interference of their scattered fields, for example, can be mitigated by adjusting the coupling or tuning of individual meta-atoms. Comprehensive numerical studies of various configurations of a resonator pair show that the coupling can lead to degenerate modes at periodic distances between the resonators. We show how the resonators' separation and relative orientation influence the coupling and thereby tunes the sound attenuation. The simulation results are supported by experiments using a two-dimensional parallel-plate waveguide. It is shown that coupling parameters like distance, orientation, detuning, and radiation loss provide additional degrees of freedom for efficient acoustic meta-atom tuning to achieve unprecedented interactions with excellent sound attenuation properties.

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A Benchmark Study on Eigenfrequencies of Fluid-Loaded Structures

Cited by 5 publications

References 38 publications

Realistic prediction and engineering of high-Q modes to implement stable Fano resonances in acoustic devices

Realistic prediction and engineering of high-Q modes to implement stable Fano resonances in acoustic devices

Sensitivity analysis of acoustic eigenfrequencies by using a boundary element method

Sound attenuation enhancement of acoustic meta-atoms via coupling

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