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Published August 22, 2002 | Published
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POD Analysis of Sound Generation by a Turbulent Jet


A Proper Orthogonal Decomposition (POD) is constructed for a Mach 0.9 turbulent jet using a well-validated direct numerical simulation database. Norms are defined based on near-field volume integrals of pressure, turbulence kinetic energy, streamwise velocity, and total enthalpy, two-dimensional integrals of streamswise velocity (to match experimental measurements), and far-field integrals of pressure over a sphere. We find substantially different POD modes for the different norms, and their efficiency at representing the full data is strongly dependent upon the norm and specifically which data we attempt to represent. To reproduce near-field turbulence statistics requires relatively few modes computed by a kinetic energy or pressure norm. However, a large number of the POD modes computed using a near-field norm are required to represent the sound field. The dominant near-field POD modes computed with either the near-field pressure norm or the sound field norm have the structure of wave packets.

Additional Information

© 2002 by J. B. Freund. Published by the American Institute of Aeronautics and Astronautics, Inc. with permission. Published Online: 22 Aug 2012. JBF gratefully acknowledges the support of NASA. Both authors acknowledge fruitful interactions with Dr. Peter Blossey whose initial computations of pressure POD modes from this database inspired the present effort.

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August 19, 2023
August 19, 2023