Propagation and Scattering in Radially Flowing Media

Abstract

—The,first-order (in v/c) vector,wave,equation,for,electro- magnetic,waves,in,moving,media,is solved,for,radially,moving,media. Two modes of flow are considered, the two-dimensional case of media flowing radially, symmetrically with respect to the z axis, and the three- dimensional,case,where,the flow,is symmetrical,with,respect,to the,origin. It is shown,that,the,solution,differs,from,the,case,of media,at rest by,a scalar multiplicative factor, involving the radius and the velocity. Propaga- tion of a plane wave is discussed, and the local behavior is interpreted in terms,of a ray,propagating,in the,moving,medium.,It is shown,that,for,an outgoing flow, the ray moves away from tbe origin in the Finite domain. At large,distances,the,ray,enters,and,emerges,from,the,medinm,in the,same direction. Scattering by a cylinder and by a sphere, symmetrical with respect to the two-, and three-dimensional flow, respectively, are dis- cussed.,It is shown,that,the,scattering,amplitude,is velocity-independent. This result,is contrasted,with,former,cases,of scattering,in moving,media.