





Volume 5, Number 2, Spring 1997
SCATTERING OF A SPHERICAL SOUND WAVE
BY A RIGID SCREEN WITH
AN ABSORBENT EDGE IN A MOVING FLUID
S. ASGHAR AND TASAWAR HAYAT
Abstract. The scattering of a spherical wave (emanating
due to a point source) by a semiinfinite plane in the presence
of a moving fluid is investigated. A finite region in the
vicinity of the edge has an absorbing boundary condition; the
remaining part of the half plane is rigid. The problem which
is solved is a mathematical model for a rigid barrier with an
absorbent edge in the presence of a moving fluid. It is found
that the absorbing material that comprises the edge need only
be of the order of a wavelength long to have approximately the
same effect on the sound attenuation in the shadow region of
the barrier as a semiinfinite absorbent barrier. Also the softer
the absorbent lining the greater the attenuation in the shadow
region of the barrier. In the illuminated region a reduction in
the sound intensity level can be achieved by a suitable choice
of the absorptive material of the strip and its length. This
investigation is important in the sense that point source is
regarded as fundamental radiating device. It is found that a
diffracted field is the sum of fields produced by the two edges.
Finally, physical interpretation of the result is discussed.
(Subscribers Only)




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