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Diffraction and Attenuation of Nonlinear Acoustic Waves in Layered Media.

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Title: Diffraction and Attenuation of Nonlinear Acoustic Waves in Layered Media.
Authors: Madhuranthakam, Yoganandh1 (AUTHOR) madhuran@msu.edu, Chakrapani, Sunil Kishore1 (AUTHOR) csk@egr.msu.edu
Source: Journal of Theoretical & Computational Acoustics. Jun2026, Vol. 34 Issue 2, p1-20. 20p.
Subjects: Wave diffraction, Attenuation (Physics), Second harmonic generation, Theory of wave motion, Model validation, Nonlinear acoustics
Abstract: Diffraction and attenuation of nonlinear acoustic waves propagating through multi-layered media are important in a wide range of applications. While many existing models address nonlinear wave propagation on a layer-by-layer basis, they often fail to adequately capture diffraction effects. To address this challenge, first, this study generalizes the current layer-wise model (limited to three layers) for n-layered media. Subsequently, three hypotheses were proposed to understand nonlinear wave propagation through layered media: (a) the presence of a single Fresnel zone for second harmonic in layered media, (b) diffraction and (c) attenuation characteristics of second harmonic wave in the 2 nd and subsequent layers. Based on these hypotheses, a unified model was developed, which accounts for both diffraction and attenuation effects. These models were examined using four cases that were designed specifically to test the hypotheses. Case I: β = 0 for layer 1, β ≠ 0 for layer 2 to determine if second harmonic in 2 nd layer will propagate in such a way that its source was at the start of second or first layer. Case II: β ≠ 0 for layer 1, β = 0 for layer 2 to check if accumulated second harmonic from 1st layer propagating as a linear wave in 2 nd layer will diffract with fundamental or second harmonic frequency. In Case III: the effect of only attenuation and no diffraction using plane wave solution. Finally in Case IV: fluid-solid two-layer case are explored. The analytical results were validated using numerical simulations, which showed that the unified model has good agreement with numerical results for all the cases compared to the layer-wise model. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
Description
Abstract:Diffraction and attenuation of nonlinear acoustic waves propagating through multi-layered media are important in a wide range of applications. While many existing models address nonlinear wave propagation on a layer-by-layer basis, they often fail to adequately capture diffraction effects. To address this challenge, first, this study generalizes the current layer-wise model (limited to three layers) for n-layered media. Subsequently, three hypotheses were proposed to understand nonlinear wave propagation through layered media: (a) the presence of a single Fresnel zone for second harmonic in layered media, (b) diffraction and (c) attenuation characteristics of second harmonic wave in the 2 nd and subsequent layers. Based on these hypotheses, a unified model was developed, which accounts for both diffraction and attenuation effects. These models were examined using four cases that were designed specifically to test the hypotheses. Case I: β = 0 for layer 1, β ≠ 0 for layer 2 to determine if second harmonic in 2 nd layer will propagate in such a way that its source was at the start of second or first layer. Case II: β ≠ 0 for layer 1, β = 0 for layer 2 to check if accumulated second harmonic from 1st layer propagating as a linear wave in 2 nd layer will diffract with fundamental or second harmonic frequency. In Case III: the effect of only attenuation and no diffraction using plane wave solution. Finally in Case IV: fluid-solid two-layer case are explored. The analytical results were validated using numerical simulations, which showed that the unified model has good agreement with numerical results for all the cases compared to the layer-wise model. [ABSTRACT FROM AUTHOR]
ISSN:25917285
DOI:10.1142/S2591728526500015