The influence of solid bodies on low Mach number vortex sound
Abstract
The mechanisms of sound generation by unsteady, subsonic flows in the presence of solid boundaries are investigated. For this purpose an alternative integral representation for the radiated pressure field is applied which is different from the generally used integral representation introduced by Lighthill and Curle. The main advantage of the method is that there is a linear dependence of the integrand on the time derivative of the vorticity fluctuations in the hydrodynamic near field; instead of the ordinary Green function a "vector Green function" is used. This vector Green function can be chosen for a given flow field in such a way that surface integrals do not appear. Finally, the theory is illustrated by two and threedimensional model flows. Analytical solutions are determined by applying the method of matched asymptotic expansions.
 Publication:

Journal of Sound Vibration
 Pub Date:
 September 1980
 DOI:
 10.1016/0022460X(80)907063
 Bibcode:
 1980JSV....72...39O
 Keywords:

 Solid Surfaces;
 Sound Generators;
 Subsonic Flow;
 Unsteady Flow;
 Vortices;
 Aerodynamic Noise;
 Asymptotic Series;
 Green'S Functions;
 Mach Number;
 Near Fields;
 Noise Generators;
 Pressure Distribution;
 Sound Pressure;
 Three Dimensional Models;
 Acoustics