Spherical wave scattering by a rigid screen with a soft edge

An analytic solution for the diffraction by a half-plane is given for a sph erical wave incidence in still air as well as in a moving fluid. This is im portant because point source is known as a fundamental radiating device. Th e half-plane is rigid except for a soft strip in the vicinity of the edge, The diffraction coefficient in both cases is strongly dependent upon freque ncy. The calculations indicate that the field is enhanced as a result of fl uid motion and this enhancement of the field is independent of the directio n of flow. It is found that the magnitude of the far field on the source si de of the semi- infinite plane seems to depend more critically on the lengt h of the soft strip and the wave number. (C) 2000 Elsevier Science Ltd. All rights reserved.