T. Colonius, S.K. Lele, P. Moin

Accurate computation of the far field sound along with the near field source terms associated with a free shear flow requires that the N avier-Stokes equations be solved using accurate numerical differentiation and time marching schemes, with non-reflecting boundary conditions. Non-reflecting boundary conditions have been developed for two dimensional linearized Euler equations by Giles (1990,AIAA J. 28 ). These conditions are modified for use with non-linear N avier-Stokes computations of open flow problems. At an outflow, vortical structures are found to produce large reflections due to non-linear effects; these reflection errors cannot be improved by increasing the accuracy of the linear boundary conditions. An exit zone, just upstream of an outflow where disturbances are significantly attenuated through grid stretching and filtering is developed for use with the non-reflecting boundary conditions; reflections from vortical structures are decreased by 3 orders of magnitude. The accuracy and stability of the boundary conditions are investigated in several model flows which include: sound radiation by an energy source in a uniformly sheared viscous flow; the propagation of vortices in a uniform flow, and the spatial evolution of a compressible mixing layer.

DGLR/AIAA 14th Aeroacoustics Conference, 1992

Conference Paper

englisch

21,0 x 29,7 cm, 10 Seiten

DGLR-Bericht, 1992, 1992-03, DGLR/AIAA 14th Aeroacoustics Conference - Proceedings; S.438-447; 1992; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn

NA

aeroacoustics, Navier-Stokes equation, boundary conditions

Bibliothek

1992