Anharmonic Solution of the Problem of Diffraction of Acoustic Waves PDF

Keywords

diffraction, acoustic wave, moving fluid

Abstract

The diffraction of an acoustic wave from a point source of sound by an absorbing half-place and a nearly half plane (y= εg (x,z); x ≤ 0 and 0 ≤ ε << 1) in the presence of a moving fluid is studied. This is done by using a recently developed method. It is assumed throughout the paper that the point source sets in at time t=0. When ε=0, it is shown that the far field of the diffracted wave is anharmonic. It behaves merely as the inverse of the distance from the point source but as if the point source movies at the fluidspeed far from the barrier. On the other hand, it is found that acoustic noise reduction by a nearly half-plane barriers y= εg (x,z); 0≤ g (x,z) ≤ 1; x ≤ 0 and -∞ < z < ∞ is better than reduction by a half-plane one.