Z. Ye et al., A METHOD FOR ACOUSTIC SCATTERING BY SLENDER BODIES .1. THEORY AND VERIFICATION, The Journal of the Acoustical Society of America, 102(4), 1997, pp. 1964-1976
This paper presents a new approach for calculating sound scattering by
slender scatterers. The method is based on the assumption that the so
und scattering function can be approximated by superimposing the scatt
ered waves from a series of small adjacent cylindrical elements, with
each of these elements scattering sound as though it were part of an i
nfinite straight cylinder of the same radius. Using the Kirchhoff inte
gral theorem, the bistatic scattering function is derived rigorously w
ithin the accuracy of the assumption. To validate the approach, the so
lution is applied to sound scattering by fluid prolate spheroids, for
which the exact solution is known. Numerical comparison with the exact
solution reveals that the new approach is very versatile; it can pred
ict scattering patterns remarkably comparable to that obtained by the
exact solution for a wide range of incident angles. For incidence with
in approximately +/-20 degrees of the broadside direction, the scatter
ing patterns predicted by the new method coincide uniformly with the e
xact results. Agreement in the absolute scattering amplitude slowly de
teriorates as the incidence is tilted away from the broadside aspect.
However, the method consistently produces scattering patterns highly c
orrelated to the results from the exact solution; this is potentially
useful for target identification based on pattern recognition techniqu
es. The results also show that the new method works better on the whol
e as the elongation of the target increases. Furthermore, calculation
of cross-correlation coefficients indicates that the present method wo
rks slightly better for rigid bodies than for weak fluid bodies. The l
ow-frequency scattering by gas-filled spheroids is also considered. It
is shown that near resonance the scattering is almost isotropic, in a
greement with the prediction of previous simple analytic solution. (C)
1997 Acoustical Society of America. [S0001-4966(97)02109-7]PACS numbe
rs: 43.20.Fn, 43.20.Tb, 43.30.Gv [JEG].