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Concentrated beams in differentially rotating and stratified fluids and their reflection at a turning point.

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Title: Concentrated beams in differentially rotating and stratified fluids and their reflection at a turning point.
Authors: Le Dizès, Stéphane1 stephane.ledizes@univ-amu.fr, Favier, Benjamin1
Source: Journal of Fluid Mechanics. 3/10/2026, Vol. 1030, p1-24. 24p.
Subjects: Gravity waves, Wave packets, Computer simulation, Rotating fluid, Fluids, Buoyancy-driven flow, Asymptotic analysis
Abstract: Concentrated wave beams are analysed both theoretically and numerically in a general rotating and stratified axisymmetric medium, where both the rotation rate and the Brunt-Väisälä frequency vary with position. The fluid is assumed to be incompressible, weakly diffusive and weakly viscous. The analysis is conducted within the Boussinesq approximation and a linear framework, with a prescribed frequency. An asymptotic solution is derived in the limit of weak viscosity and diffusivity, describing a harmonic beam of inertia gravity waves localised around a characteristic (or ray path), similar to those generated by boundary singularities or critical points. This solution is shown to break down when the characteristic reaches a turning point which corresponds to the transition from oscillatory to evanescent behaviour. A local asymptotic analysis near the turning point demonstrates that the wave beam reflects, preserving its transverse structure while acquiring a phase shift of ±π/2. These theoretical predictions are validated through numerical simulations, which show that the wave beam structure, both near and far from the turning point, is accurately reproduced. [ABSTRACT FROM AUTHOR]
Copyright of Journal of Fluid Mechanics is the property of Cambridge University Press 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: 192858547
AccessLevel: 6
PubType: Academic Journal
PubTypeId: academicJournal
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  Data: Concentrated beams in differentially rotating and stratified fluids and their reflection at a turning point.
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  Data: <searchLink fieldCode="AR" term="%22Le+Dizès%2C+Stéphane%22">Le Dizès, Stéphane</searchLink><relatesTo>1</relatesTo><i> stephane.ledizes@univ-amu.fr</i><br /><searchLink fieldCode="AR" term="%22Favier%2C+Benjamin%22">Favier, Benjamin</searchLink><relatesTo>1</relatesTo>
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  Data: <searchLink fieldCode="JN" term="%22Journal+of+Fluid+Mechanics%22">Journal of Fluid Mechanics</searchLink>. 3/10/2026, Vol. 1030, p1-24. 24p.
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  Data: <searchLink fieldCode="DE" term="%22Gravity+waves%22">Gravity waves</searchLink><br /><searchLink fieldCode="DE" term="%22Wave+packets%22">Wave packets</searchLink><br /><searchLink fieldCode="DE" term="%22Computer+simulation%22">Computer simulation</searchLink><br /><searchLink fieldCode="DE" term="%22Rotating+fluid%22">Rotating fluid</searchLink><br /><searchLink fieldCode="DE" term="%22Fluids%22">Fluids</searchLink><br /><searchLink fieldCode="DE" term="%22Buoyancy-driven+flow%22">Buoyancy-driven flow</searchLink><br /><searchLink fieldCode="DE" term="%22Asymptotic+analysis%22">Asymptotic analysis</searchLink>
– Name: Abstract
  Label: Abstract
  Group: Ab
  Data: Concentrated wave beams are analysed both theoretically and numerically in a general rotating and stratified axisymmetric medium, where both the rotation rate and the Brunt-Väisälä frequency vary with position. The fluid is assumed to be incompressible, weakly diffusive and weakly viscous. The analysis is conducted within the Boussinesq approximation and a linear framework, with a prescribed frequency. An asymptotic solution is derived in the limit of weak viscosity and diffusivity, describing a harmonic beam of inertia gravity waves localised around a characteristic (or ray path), similar to those generated by boundary singularities or critical points. This solution is shown to break down when the characteristic reaches a turning point which corresponds to the transition from oscillatory to evanescent behaviour. A local asymptotic analysis near the turning point demonstrates that the wave beam reflects, preserving its transverse structure while acquiring a phase shift of ±π/2. These theoretical predictions are validated through numerical simulations, which show that the wave beam structure, both near and far from the turning point, is accurately reproduced. [ABSTRACT FROM AUTHOR]
– Name: AbstractSuppliedCopyright
  Label:
  Group: Ab
  Data: <i>Copyright of Journal of Fluid Mechanics is the property of Cambridge University Press 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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      – Type: doi
        Value: 10.1017/jfm.2026.11219
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      – Code: eng
        Text: English
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        PageCount: 24
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      – SubjectFull: Gravity waves
        Type: general
      – SubjectFull: Wave packets
        Type: general
      – SubjectFull: Computer simulation
        Type: general
      – SubjectFull: Rotating fluid
        Type: general
      – SubjectFull: Fluids
        Type: general
      – SubjectFull: Buoyancy-driven flow
        Type: general
      – SubjectFull: Asymptotic analysis
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      – TitleFull: Concentrated beams in differentially rotating and stratified fluids and their reflection at a turning point.
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            NameFull: Favier, Benjamin
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            – D: 10
              M: 03
              Text: 3/10/2026
              Type: published
              Y: 2026
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