### ASA 127th Meeting M.I.T. 1994 June 6-10

## 2aPA14. On sound diffraction by an impedance wedge.

**Andrey V. Osipov
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*Radiophys. Dept., Inst. of Phys., St. Petersburg State Univ., Ulianovskaya
1-1, 198904 St. Petersburg, Russia
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Diffraction of waves by a wedge is one of the several canonical problems
of modern acoustics whose mathematical solutions provide a theoretical basis in
analyzing sound radiation and scattering phenomena. Starting from Sommerfeld's
classical works, considerable attention has been attracted to this class of
diffraction problems, especially to the particular cases of a perfectly
reflecting wedge and half-plane [W. J. Hadden and A. D. Pierce, J. Acoust. Soc.
Am. 69, 1266 (1981); R. P. Kendig and S. I. Hayek, J. Acoust. Soc. Am. 70, 1156
(1981)]. The model of an impedance wedge [G. D. Malyuzhinets, 1958 Dokl. Akad.
Nauk SSSR 121, 436 (1958) in Russian] is a more general and realistic one that
gives new opportunities for treating acoustic diffraction by irregular surfaces
[A. D. Pierce and W. J. Hadden, J. Acoust. Soc. Am. 63, 17 (1978); A. V.
Osipov, Sov. Phys. Acoust. 36, 287 (1990)]. This paper investigates the wave
field excited by a line source in the presence of a wedge with arbitrary values
of face impedances. Based on the Malyuzhinets' solution, various exact
representations for the Green's function are deduced to generate a system of
convenient formulas for any relative positions of the source and point of
observation. A new representation of the Malyuzhinets' solution in the form of
double series [A. V. Osipov, Sov. Phys. Acoust. 37, 381 (1991)] is exploited to
describe the wave field of the line source placed in the vicinity of edge. In
the opposite case of large distances from the edge, a uniform asymptotic
expansion is presented that remains to be correct at shadow boundaries.
Applications of the obtained results to problems of sound attenuation by
wedge-like barriers and sound radiation from a line source located at the edge
of a corrugated surface depending on the values of face impedances are
described.

All posters will be on display from 8:00 a.m. to 12:00 noon. To allow
contributors an opportunity to see other posters, contributors of odd-numbered
posters will be at their posters from 8:00 a.m. to 10:00 a.m. and contributors
of even-numbered posters will be at their posters from 10:00 a.m. to 12:00
noon.