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

## 4aSA9. Numerical estimates---based on ray methods---for the scattered
acoustic fields of pairs of targets.

**G. C. Gaunaurd
**

**
H. Huang
**

**
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*Naval Surface Warfare Ctr., Dahlgren Div., Res. Dept., Silver Spring, MD
20903-5640
*

*
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**H. C. Strifors
**

**
**
*Natl. Defense Res. Establishment, S-17290, Sundbyberg, Sweden
*

*
*
The sounds fields scattered by a multiplicity of spherical bodies can be
predicted in an exact analytic fashion. This was illustrated in a previous
presentation (cf., the paper entitled ``Exact Analysis of the Acoustic
Scattering Produced by Arbitrarily Insonified Bodies Near Boundaries,'' by
Huang and Gaunaurd (in this session), which also included the exact analysis
for two spheres in free space, at arbitrary frequencies, and accounting for
multiple scattering interactions. That work was mainly concerned with the low-
and mid-frequency regimes. However, at the high frequencies for which certain
asymptotic approximations begin to hold true, one can construct relatively
simple-looking expressions for the sound fields scattered by pairs of spherical
bodies. These expressions become even simpler looking for bodies separated by
distances larger than their sizes. Even when this is not the case, the
asymptotic results seem to hold just as well. The final estimates are: (a)
evaluated numerically, (b) compared to (now available) exact analytic
solutions, (c) graphically displayed, and (d) physically interpreted. These
estimates are the acoustical counterparts of analogous ones in the radar
literature and they are useful to determine the minimal separation at which
remote sensors can actually discriminate two (or more) interacting neighboring
targets. [Work partially supported by the NSWC IR Program.]