A Caltech Library Service

The Sound Generated by a Two-Dimensional Shear Layer: A Comparison of Direct Computations and Acoustic Analogies

Colonius, Tim and Lele, Sanjiva K. and Moin, Parviz (1995) The Sound Generated by a Two-Dimensional Shear Layer: A Comparison of Direct Computations and Acoustic Analogies. In: First Joint CEAS/AIAA Aeroacoustics Conference (16th AIAA Aeroacoustics Conference) Proceedings. Deutsche Gesellschaft für Luft- und Raumfahrt , Bonn, Germany. ISBN 9783922010852.

[img] PDF - Submitted Version
See Usage Policy.


Use this Persistent URL to link to this item:


The sound generated by vortex pairing in a two-dimensional mixing layer is studied by solving the Navier-Stokes equations (DNS) for the layer and a portion of its acoustic field, and by solving acoustic analogies with source terms determined from the DNS. Predictions for the acoustic field based on Lilley’s equation are in excellent agreement with the DNS results giving detailed verification of Lilley’s acoustic analogy for the first time. We show that parts of the full source term which arise when the left-hand-side of Lilley’s equation is linearized should not be neglected solely because they are attributable to refraction and scattering, nor because they are proportional to the dilatation. Lilley’s source, -2u_(i,j)u_(j,k)u_(k,i), appears to be mainly responsible for the overall directivity of the acoustic field produced by the vortex pairings, which is highly focused at shallow angles to the streamwise axis. Scattering of the waves by the flow appears also to be significant, causing the directivity to be more omnidirectional than the Lilley source alone would predict. We also show how small errors in determining the sources, especially those due to scattering, can sometimes lead to large errors in the predictions.

Item Type:Book Section
Colonius, Tim0000-0003-0326-3909
Moin, Parviz0000-0002-0491-7065
Additional Information:© 1995 Deutsche Gesellschaft für Luft- und Raumfahrt. This work has been sponsored by the Office of Naval Research, grant N00014-92-J-1626, and computer time and support has been provided by the NASA Ames Research Center and the Center for Turbulence Research.
Funding AgencyGrant Number
Office of Naval Research (ONR)N00014-92-J-1626
Record Number:CaltechAUTHORS:20190726-104730109
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:97457
Deposited By: Melissa Ray
Deposited On:31 Jul 2019 22:51
Last Modified:20 Mar 2021 00:33

Repository Staff Only: item control page