### Abstract

Sound transmisslon through straight circular duels with a uniform (inviscid) mean flow and a constant acoustic lining (impedance wall) is classicaIly described by a modal expansion. A natural extansion for ducts with, in axial direction. slowly varying properties (Iike diameter. wall impedance, and mean flow) is a muttiple-scales solution. It is shown in the present paper that a consistent
approximation ol boundary condition and mean flow allows the multiple-scales problem to have an exact soIution. Tuming points and other singularities of this soIulion are discussed.

Original language | English |
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Pages (from-to) | 157-167 |

Journal | Nieuw Archief voor Wiskunde |

Volume | 4/6 |

Issue number | 1-2 |

Publication status | Published - 1988 |

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## Cite this

Rienstra, S. W. (1988). Sound transmission in a slowly varying lined flow duct.

*Nieuw Archief voor Wiskunde*,*4/6*(1-2), 157-167.