Amplitude Scaling of Wave Packets in Turbulent Jets

This paper studies the amplitude of large-scale coherent wave-packet structures in jets, modeled by the parabolized stability equations (PSEs). Linear PSEs can retrieve the shape of the wave packets, but linearity leads to solutions with a free amplitude, which has traditionally been obtained in an...

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Bibliographic Details
Published in:AIAA journal 2021-02, Vol.59 (2), p.559-568
Main Authors: Antonialli, Luigi A, Cavalieri, André V. G, Schmidt, Oliver T, Colonius, Tim, Jordan, Peter, Towne, Aaron, Brès, Guillaume A
Format: Article
Language:English
Subjects:
Amplitudes
Large eddy simulation
Linearity
Parabolized stability equations
Proper Orthogonal Decomposition
Strouhal number
Turbulent jets
Wave packets
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Summary:This paper studies the amplitude of large-scale coherent wave-packet structures in jets, modeled by the parabolized stability equations (PSEs). Linear PSEs can retrieve the shape of the wave packets, but linearity leads to solutions with a free amplitude, which has traditionally been obtained in an ad hoc manner using limited data. We systematically determine the free amplitude as a function of frequency and azimuthal wave number by comparing the fluctuation fields retrieved from PSEs with coherent structures educed from large-eddy simulation data using spectral proper orthogonal decomposition. The wave-packet amplitude is shown to decay exponentially with the Strouhal number for axisymmetric and helical modes at both Mach numbers considered in the study: 0.4 and 0.9. Analytical fit functions are proposed, and the scaled wave packets provide reasonable reconstructions of pressure and velocity spectra on the jet centerline and lip line over a range of streamwise positions.
ISSN:0001-1452
1533-385X
DOI:10.2514/1.J059599