A weakly nonlinear wave equation for damped acoustic waves with thermodynamic non-equilibrium effects

The problem of propagating nonlinear acoustic waves is considered; the solution to which, both with and without damping, having been obtained to-date starting from the Navier–Stokes–Duhem equations together with the continuity and thermal conduction equation. The novel approach reported here adopts...

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Veröffentlicht in:Wave motion 2022-02, Vol.109, p.102876, Article 102876
1. Verfasser: Scholle, M.
Format: Artikel
Sprache:eng
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Zusammenfassung:The problem of propagating nonlinear acoustic waves is considered; the solution to which, both with and without damping, having been obtained to-date starting from the Navier–Stokes–Duhem equations together with the continuity and thermal conduction equation. The novel approach reported here adopts instead, a discontinuous Lagrangian approach, i.e. from Hamilton’s principle together with a discontinuous Lagrangian for the case of a general viscous flow. It is shown that ensemble averaging of the equation of motion resulting from the Euler–Lagrange equations, under the assumption of irrotational flow, leads to a weakly nonlinear wave equation for the velocity potential: in effect a generalisation of Kuznetsov’s well known equation with an additional term due to thermodynamic non-equilibrium effects. •Viscous flow with thermal conduction is deducible from a discontinuous Lagrangian.•Non-classical effects occur beyond thermodynamic equilibrium.•By ensemble averaging a non-classical equation of motion is derived.•In the irrotational and weakly nonlinear case a generalised Kuznetsov equation is obtained.
ISSN:0165-2125
1878-433X
DOI:10.1016/j.wavemoti.2021.102876