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A study of aliasing error in DGM solutions to turbofan exhaust noise problems

A study of aliasing error in DGM solutions to turbofan exhaust noise problems
A study of aliasing error in DGM solutions to turbofan exhaust noise problems
Highly non-uniform flows such as shear layers are an intrinsic feature of turbofan exhaust noise problems. Modeling the sound radiation from turbofan exhausts with the linearized Euler equations raises the issue of accurately representing strongly spatially-varying mean flows numerically, while ensuring that numerical solutions are not polluted by spurious solutions such as aliasing errors. This paper investigates the behavior of aliasing instabilities in time domain solutions obtained by the discontinuous Galerkin method. A model exhaust noise problem is studied to demonstrate the growth of unphysical temporal instabilities. A new fully-discrete dispersion analysis technique is developed that permits non-uniform mean flows. The dispersion analysis is used to study the spectral behavior of aliasing instabilities and the impact of polynomial order on their formation and growth. The results of this study indicate that aliasing errors are largely absolute instabilities which build up in the solution over time and are highly sensitive to the polynomial order.
Williamschen, Michael
021ce84d-c07d-4a48-9d8e-5cc38d6ccc23
Gabard, Gwenael
bfd82aee-20f2-4e2c-ad92-087dc8ff6ce7
Beriot, Hadrien
af5a12ac-8347-48b9-9e15-9319a59163a9
Williamschen, Michael
021ce84d-c07d-4a48-9d8e-5cc38d6ccc23
Gabard, Gwenael
bfd82aee-20f2-4e2c-ad92-087dc8ff6ce7
Beriot, Hadrien
af5a12ac-8347-48b9-9e15-9319a59163a9

Williamschen, Michael, Gabard, Gwenael and Beriot, Hadrien (2015) A study of aliasing error in DGM solutions to turbofan exhaust noise problems. 22nd International Congress on Sound and Vibration (ICSV22), Italy. 12 - 16 Jul 2015. 8 pp .

Record type: Conference or Workshop Item (Other)

Abstract

Highly non-uniform flows such as shear layers are an intrinsic feature of turbofan exhaust noise problems. Modeling the sound radiation from turbofan exhausts with the linearized Euler equations raises the issue of accurately representing strongly spatially-varying mean flows numerically, while ensuring that numerical solutions are not polluted by spurious solutions such as aliasing errors. This paper investigates the behavior of aliasing instabilities in time domain solutions obtained by the discontinuous Galerkin method. A model exhaust noise problem is studied to demonstrate the growth of unphysical temporal instabilities. A new fully-discrete dispersion analysis technique is developed that permits non-uniform mean flows. The dispersion analysis is used to study the spectral behavior of aliasing instabilities and the impact of polynomial order on their formation and growth. The results of this study indicate that aliasing errors are largely absolute instabilities which build up in the solution over time and are highly sensitive to the polynomial order.

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Published date: 12 July 2015
Venue - Dates: 22nd International Congress on Sound and Vibration (ICSV22), Italy, 2015-07-12 - 2015-07-16
Organisations: Acoustics Group

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Local EPrints ID: 381473
URI: https://eprints.soton.ac.uk/id/eprint/381473
PURE UUID: 739de578-02fc-4f70-8c1b-ffaa1496680c

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Date deposited: 29 Sep 2015 10:45
Last modified: 19 Jul 2019 20:33

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