Bifurcation in compressible moving fluids and suppressing atmospheric turbulence of aircraft-flow amplifies sound.
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| Title: | Bifurcation in compressible moving fluids and suppressing atmospheric turbulence of aircraft-flow amplifies sound. |
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| Authors: | Qian, Zuwen1 qianzw@mail.ioa.ac.cn |
| Source: | Sound & Vibration. 2026, Vol. 60 Issue 2, p1-24. 24p. |
| Subjects: | Compressible flow, Wave amplification, Mach number, Fluid dynamics, Atmospheric turbulence, Bifurcation theory, Nonlinear waves |
| Abstract: | Quasi-accumulation solutions for acoustic waves in a compressible moving fluid are obtained by applying the Lagrange parameter variation method to solve the Lighthill equation. The results demonstrate that nonlinear interactions lead first to period-doubling, followed by odd multiple half-period bifurcations, with all-order sub-harmonics subsequently generated. The amplitudes of these sub-harmonics depend not only on the acoustic Mach number but also on the Mach number of the flow. The latter result indicates that the acoustic wave has been amplified by the momentum of the flow. Furthermore, the relationship between the amplification gain of sub-harmonics and flow velocity is a polynomial function of flow-sound Mach number ratio M/m. If the kinetic energy gained through momentum amplification exceeds the energy loss due to the acoustic attenuation, a chain-reaction of the period-doubling followed by the odd multiple half-period bifurcation can be sustained. As the order number of the approximation m1 increases, the number of degrees of freedom in the flow increases infinitely and the leading terms of the amplitudes for the generated sub-harmonics which are proportional to M m k/2α)... approach to infinity, where M and m, k and a are Mach number for flow and sound, the wave-number and absorption coefficient, respectively. The obtained results also indicate that the appropriate control parameter for transitioning from bifurcation to chaos should be k/α instead of Reynolds number Re. This paper also demonstrates that in the moving fluid sound waves can be amplified through nonlinear interactions, particularly, the first sub-harmonic generates, thereby explaining the experimental results we discovered decades ago. Finally, a potential strategy for suppressing aircraft-induced atmospheric turbulence is proposed based on the present theoretical findings. [ABSTRACT FROM AUTHOR] |
| Copyright of Sound & Vibration is the property of Academic Publishing and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
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| Header | DbId: egs DbLabel: Engineering Source An: 193687723 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Bifurcation in compressible moving fluids and suppressing atmospheric turbulence of aircraft-flow amplifies sound. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Qian%2C+Zuwen%22">Qian, Zuwen</searchLink><relatesTo>1</relatesTo><i> qianzw@mail.ioa.ac.cn</i> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Sound+%26+Vibration%22">Sound & Vibration</searchLink>. 2026, Vol. 60 Issue 2, p1-24. 24p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Compressible+flow%22">Compressible flow</searchLink><br /><searchLink fieldCode="DE" term="%22Wave+amplification%22">Wave amplification</searchLink><br /><searchLink fieldCode="DE" term="%22Mach+number%22">Mach number</searchLink><br /><searchLink fieldCode="DE" term="%22Fluid+dynamics%22">Fluid dynamics</searchLink><br /><searchLink fieldCode="DE" term="%22Atmospheric+turbulence%22">Atmospheric turbulence</searchLink><br /><searchLink fieldCode="DE" term="%22Bifurcation+theory%22">Bifurcation theory</searchLink><br /><searchLink fieldCode="DE" term="%22Nonlinear+waves%22">Nonlinear waves</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Quasi-accumulation solutions for acoustic waves in a compressible moving fluid are obtained by applying the Lagrange parameter variation method to solve the Lighthill equation. The results demonstrate that nonlinear interactions lead first to period-doubling, followed by odd multiple half-period bifurcations, with all-order sub-harmonics subsequently generated. The amplitudes of these sub-harmonics depend not only on the acoustic Mach number but also on the Mach number of the flow. The latter result indicates that the acoustic wave has been amplified by the momentum of the flow. Furthermore, the relationship between the amplification gain of sub-harmonics and flow velocity is a polynomial function of flow-sound Mach number ratio M/m. If the kinetic energy gained through momentum amplification exceeds the energy loss due to the acoustic attenuation, a chain-reaction of the period-doubling followed by the odd multiple half-period bifurcation can be sustained. As the order number of the approximation m1 increases, the number of degrees of freedom in the flow increases infinitely and the leading terms of the amplitudes for the generated sub-harmonics which are proportional to M m k/2α)... approach to infinity, where M and m, k and a are Mach number for flow and sound, the wave-number and absorption coefficient, respectively. The obtained results also indicate that the appropriate control parameter for transitioning from bifurcation to chaos should be k/α instead of Reynolds number Re. This paper also demonstrates that in the moving fluid sound waves can be amplified through nonlinear interactions, particularly, the first sub-harmonic generates, thereby explaining the experimental results we discovered decades ago. Finally, a potential strategy for suppressing aircraft-induced atmospheric turbulence is proposed based on the present theoretical findings. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Sound & Vibration is the property of Academic Publishing and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.59400/sv3837 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 24 StartPage: 1 Subjects: – SubjectFull: Compressible flow Type: general – SubjectFull: Wave amplification Type: general – SubjectFull: Mach number Type: general – SubjectFull: Fluid dynamics Type: general – SubjectFull: Atmospheric turbulence Type: general – SubjectFull: Bifurcation theory Type: general – SubjectFull: Nonlinear waves Type: general Titles: – TitleFull: Bifurcation in compressible moving fluids and suppressing atmospheric turbulence of aircraft-flow amplifies sound. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Qian, Zuwen IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 03 Text: 2026 Type: published Y: 2026 Identifiers: – Type: issn-print Value: 15410161 Numbering: – Type: volume Value: 60 – Type: issue Value: 2 Titles: – TitleFull: Sound & Vibration Type: main |
| ResultId | 1 |
