Vortex element method-expansion about incompressible flow computation of noise generation by subsonic shear flows - the impact of external forcing

Abstract

Efficient computation of noise generation by shear flows is achieved using a model that employs the vortex element method (VEM) to reproduce the unsteady incompressible flow dynamics and the expansion about incompressible flow (EIF) technique to capture the acoustic field. Several strategies in coupling the VEM with the EIF approach are proposed. The VEM-EIF model is demonstrated by computing the sound generation due to a forced as well as an unforced planar shear layer. Results for the forced case compare favourably with previous computational evidence. They exhibit a preferential directivity for the subharmonic frequency of the mostunstable flow frequency in the region just below the streamwise coordinate axis. The unforced flow results exhibit a qualitatively similar behaviour, suggesting that the beaming of subharmonic noise is not an artifact of the forcing.

Present address: United Technologies Research Center, East Hartford, CT 06108, USA.

This article was chosen from Selected Proceedings of the 4th International Workshop on Vortex Flows and Related Numerical Methods (UC Santa-Barbara, 17-20 March 2002) ed E Meiburg, G H Cottet, A Ghoniem and P Koumoutsakos.

Present address: Electric Boat Corporation, Groton, CT 06340-4989, USA.

Notes

Present address: United Technologies Research Center, East Hartford, CT 06108, USA.

Present address: Electric Boat Corporation, Groton, CT 06340-4989, USA.