GAUSSIAN SERIES SOLUTION FOR SONIC BLACK HOLES IN DUCT TERMINATIONS

Jie Deng, Oriol Guasch, Davide Ghilardi

Research output: Book chapterConference contributionpeer-review

Abstract

Sonic black holes (ABHs) at duct terminations slow down impinging waves by means of a set of rings separated by cavities, whose inner radii diminish following a power law profile. Energy tends to concentrate at the end of the waveguide and is dissipated by visco-thermal losses, resulting in a very low reflection coefficient. This anechoic behavior is governed by a modified Webster equation that takes into account the wave propagation inside the duct of variable cross section and wall admittance. In this paper it is shown that the generalised Webster equation can be transformed into a Helmholtz-type equation with non-constant wave number. We solve its weak form by expanding the solution in terms of Gaussian functions and show how the modal distribution within the SBH affects the occurrence and disappearance of peaks and dips in the SBH reflection coefficient.

Original languageEnglish
Title of host publicationForum Acusticum 2023 - 10th Convention of the European Acoustics Association, EAA 2023
PublisherEuropean Acoustics Association, EAA
ISBN (Electronic)9788888942674
Publication statusPublished - 2023
Event10th Convention of the European Acoustics Association, EAA 2023 - Torino, Italy
Duration: 11 Sept 202315 Sept 2023

Publication series

NameProceedings of Forum Acusticum
ISSN (Print)2221-3767

Conference

Conference10th Convention of the European Acoustics Association, EAA 2023
Country/TerritoryItaly
CityTorino
Period11/09/2315/09/23

Keywords

  • acoustic black hole
  • anechoic termination
  • slow sound
  • sonic black holes
  • waveguide

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