Scattering and diffraction of sound by moving bodies

Publisher Website
Google Scholar
Abstract
A scattering configuration consists of a primary acoustic source S and a scattering body B, and we examine the effect of convection of S and B, at a uniform subsonic Mach number M, on the scattered field, for various types of source and scatterer. It is shown that if B is a compact rigid body scattering the near field of the source S it is not equivalent to a convected point dipole, but rather its pressure field is augmented by the quadrupole convection factor (1 − M cosθ)−3. If, on the other hand, the compact body B scatters the distant field of S, convective effects introduce an O(M) monopole field which does not vanish in the sideline directions. A number of problems are examined in which B is a rigid half-plane, and there it is shown that the effect of convection is to augment the pressure by for scattering of the near field of S. Effects associated with the multipole order of S are discussed, as are those arising from the satisfaction of a Kutta condition at the trailing edge of the half-plane, and the application of these results to current problems in aerodynamic sound is mentioned.

This publication has 8 references indexed in Scilit: