{
  "abstract": "A compressible fluid column between two thin elastic plates carrying plane Poiseuille flow supports discrete structural-acoustic wall modes. This paper analyses their coupled dispersion and reports a flow-induced instability. Because a no-slip profile has zero velocity at the wall, the convective (Ingard-Myers) term in the compliant-wall boundary condition vanishes identically, so the plate-admittance conditions stay Mach-independent and a Fredholm solvability argument yields a closed-form $O(M)$ correction to every coupled wavenumber, valid for any smooth no-slip shear profile. Above the critical Mach number $M_c=Ω/ξ$ at which an interior critical layer first appears, the two structural branches behave oppositely. The antisymmetric mode is not absorbed by the critical layer, a null protected by an exact mid-plane pressure node rather than by weak coupling. The symmetric mode, which carries no such node, is convectively unstable. Its growth rate, fixed both by a spatial calculation anchored to the dissipative wall-Stokes term and by a convention-independent temporal one, strengthens towards the inviscid limit, identifying an inviscid critical-layer instability rather than a viscous artefact. A Briggs-Bers analysis classifies it as convective. Its neutral curve follows $M_c(Ω)$, and its growth rate is proportional to the wall compliance, vanishing for rigid walls, so it is distinct from the Tollmien-Schlichting and Kelvin-Helmholtz mechanisms. Three independent numerical schemes agree to one part in $10^9$, and the closed-form correction matches numerical differentiation across three shear profiles.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.10798",
  "author_total": 1,
  "authors": [
    {
      "name": "Ashray Saxena"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/dqhanr7m9f2h4.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.10798",
  "fulltext_url": null,
  "id": "dqhanr7m9f2h4",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.10798",
  "language": null,
  "licence": "CC-BY-NC-SA-4.0",
  "licence_label": "CC BY-NC-SA 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by-nc-sa/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "physics.flu-dyn"
    ],
    [
      "openalex",
      "2202|Aerodynamics and Acoustics in Jet Flows"
    ]
  ],
  "openalex": "W7221134219",
  "pdf_url": "https://arxiv.org/pdf/2610.10798",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-07",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/dqhanr7m9f2h4.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:27:54Z",
      "native_id": "2610.10798",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.10798"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:physics.flu-dyn",
      "subfield": "fluid-dynamics"
    }
  ],
  "title": "A critical-layer instability of structural acoustic wall modes in a two-flexible-plate channel with Poiseuille flow: closed-form low-Mach corrections and parity-protected absorption",
  "title_text": "A critical-layer instability of structural acoustic wall modes in a two-flexible-plate channel with Poiseuille flow: closed-form low-Mach corrections and parity-protected absorption",
  "type": "preprint",
  "updated_at": "2026-10-30T12:27:54Z",
  "url": "https://research.draconitic.com/paper/dqhanr7m9f2h4",
  "venue": "arXiv",
  "versions": []
}