Impedance-to-scattering matrix method for large silencer analysis using direct collocation

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Large silencers used in industry usually have a very large cross section at the inlet and outlet. Higher-order modes will populate the inlet and outlet even at very low frequencies. A three-dimensional analysis tool, such as the finite element method or the boundary element method, must incorporate certain forms of modal expansion in order to consider the higher-order modes in the transmission loss computation. In this paper, the impedance matrix obtained from the sub-structured boundary element method is converted into the scattering matrix that relates the higher-order modes. Since there are always more boundary elements at the inlet and outlet than the total number of propagating modes, a least-squares procedure is used to convert the element-based impedance matrix into the modal expansion-based scattering matrix. The transmission loss of the silencer can then be computed from the scattering matrix if a certain form of the incident wave is assumed. Furthermore, a slightly rearranged form of the scattering matrix may also be used to combine subsystems in series connection.

Original languageEnglish
Pages (from-to)191-199
Number of pages9
JournalEngineering Analysis with Boundary Elements
StatePublished - Dec 1 2016

Bibliographical note

Funding Information:
The research was partially supported by the Vibro-Acoustics Consortium.

Publisher Copyright:
© 2016 Elsevier Ltd


  • Boundary element method
  • Impedance matrix
  • Large silencers
  • Scattering matrix

ASJC Scopus subject areas

  • Analysis
  • Engineering (all)
  • Computational Mathematics
  • Applied Mathematics


Dive into the research topics of 'Impedance-to-scattering matrix method for large silencer analysis using direct collocation'. Together they form a unique fingerprint.

Cite this