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Sound generation in a mixing layer

Colonius, Tim and Lele, Sanjiva K. and Moin, Parviz (1997) Sound generation in a mixing layer. Journal of Fluid Mechanics, 330 . pp. 375-409. ISSN 0022-1120. http://resolver.caltech.edu/CaltechAUTHORS:COLjfm97

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Abstract

The sound generated by vortex pairing in a two-dimensional compressible mixing layer is investigated. Direct numerical simulations (DNS) of the Navier-Stokes equations are used to compute both the near-field region and a portion of the acoustic field. The acoustic analogy due to Lilley (1974) is also solved with acoustic sources determined from the near-field data of the DNS. It is shown that several commonly made simplifications to the acoustic sources can lead to erroneous predictions for the acoustic field. Predictions based on the quadrupole form of the source terms derived by Goldstein (1976a, 1984) are in excellent agreement with the acoustic field from the DNS. However, despite the low Mach number of the flow, the acoustic far field generated by the vortex pairings cannot be described by considering compact quadrupole sources. The acoustic sources have the form of modulated wave packets and the acoustic far field is described by a superdirective model (Crighton & Huerre 1990). The presence of flow-acoustic interactions in the computed source terms causes the acoustic field predicted by the acoustic analogy to be very sensitive to small changes in the description of the source.


Item Type:Article
Additional Information:"Reprinted with the permission of Cambridge University Press." Received September 7 1995; revised August 22 1996. The authors are grateful to Professor Geoffrey Lilley for his helpful remarks on a draft of this paper. Part of this work was completed under grants ONR-N00014-88-K-0592 and ONR-N00014-92-J-1626 from the Office of Naval Research, while the first author was a graduate student at Stanford University. The first author is also grateful for recent support from the National Science Foundation under grant number CTS-9501349. Supercomputing time and support was provided by NASA-Ames Research Center and the Center for Turbulence Research. Some of the work presented here was presented in preliminary form in AIAA Paper 93-4328, CEAS/AIAA Paper 95-036, and ASME FED-Vol. 219.
Subject Keywords:NONREFLECTING BOUNDARY-CONDITIONS; DIRECT COMPUTATION; SHEAR-LAYER; JET; NOISE; VORTEX; WAVES
Record Number:CaltechAUTHORS:COLjfm97
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:COLjfm97
Alternative URL:http://www.journals.cambridge.org/action/displayAbstract?fromPage=online&aid=13051
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:2289
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:22 Mar 2006
Last Modified:26 Dec 2012 08:48

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