Convergence of modes in exterior acoustics problems with infinite elements

Lennart Moheit, Steffen Marburg

Publikation: KonferenzbeitragPapierBegutachtung

Abstract

The radiated sound power is seldom computed by modal decomposition, since modal quantities are uncommon in exterior acoustics problems. The Finite Element Method and the Infinite Element Method (FEM and IFEM) are applied in order to discretize an unbounded fluid-filled domain and to obtain system matrices that are independent of frequency. From these system matrices of mass, damping and stiffness, frequency-independent normal modes are computed as right eigenvectors of a state-space eigenvalue problem. As the polynomial order of radial interpolation in the domain of the infinite elements increases, the normal mode eigenvalues converge and lead to reliable results for the radiated sound power in exemplary load cases. However, the additional degrees of freedom may also yield mathematical artifacts or spurious modes, which might falsify the calculated sound power in the case of modal superposition. By application of the Modal Assurance Criterion (MAC), significant and converged modes are identified and their contribution to the total radiated sound power is investigated.

OriginalspracheEnglisch
Seiten1640-1648
Seitenumfang9
PublikationsstatusVeröffentlicht - 21 Aug. 2016
Veranstaltung45th International Congress and Exposition on Noise Control Engineering: Towards a Quieter Future, INTER-NOISE 2016 - Hamburg, Deutschland
Dauer: 21 Aug. 201624 Aug. 2016

Konferenz

Konferenz45th International Congress and Exposition on Noise Control Engineering: Towards a Quieter Future, INTER-NOISE 2016
Land/GebietDeutschland
OrtHamburg
Zeitraum21/08/1624/08/16

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