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The proper orthogonal decomposition of pressure fluctuations surrounding a turbulent jet
Arndt, Roger E.A.; Long, D.F.; Glauser, M.N (Cambridge University Press, 1997)
 

Title 
The proper orthogonal decomposition of pressure fluctuations surrounding a turbulent jet

Issue Date
1997

Publisher
Cambridge University Press

Type
Article

Abstract
It is shown that the pressure signal measured at the outer edge of a jet mixing layer is entirely hydrodynamic in nature and provides a good measure of the large-scale structure of the turbulent flow. Measurement of the pressure signal provides a unique opportunity to utilize proper orthogonal decomposition (POD) to deduce the streamwise structure. Since pressure is a scalar, a significant reduction in the numerical and experimental complexity inherent in the analysis of velocity vector fields results. The POD streamwise eigenfunctions show that the structure associated with any frequency–azimuthal mode number combination displays the general characteristics of amplification–saturation–decay of an instability wave, all within about three wavelengths. High-frequency components saturate early in x and low-frequency components saturate further downstream, indicative of the inhomogeneous character of the flow in the streamwise direction. Application of the POD technique allows the phase velocity to be determined taking into account the inhomogeneity of the flow in the streamwise direction. The phase velocity of each instability wave (POD eigenvector) is constant and equal to 0.58Uj , indicating that the jet structure is non-dispersive. Using the shot-noise decomposition, a characteristic event is constructed. This event is found to contain evidence of both pairings and triplings of vortex structures. The tripling results in a rapid increase in the first asymmetric (m = 1) component. On average, pairing occurs once every four Uj/D while tripling occurs once every 13Uj/D.

Appears in Collection(s)

Description
Copyright Cambridge University Press. Published article may be found at http://journals.cambridge.org/action/displayAbstract?aid=13425.

Sponsorship
Air Force Office of Scientific Research, Office of Naval Research

Suggested Citation
Arndt, Roger E.A.; Long, D.F.; Glauser, M.N. (1997). The proper orthogonal decomposition of pressure fluctuations surrounding a turbulent jet. Cambridge University Press. Retrieved from the University of Minnesota Digital Conservancy, http://purl.umn.edu/49807.


Content distributed via the University of Minnesota's Digital Conservancy may be subject to additional license and use restrictions applied by the depositor.