### ASA 126th Meeting Denver 1993 October 4-8

## 4pSA7. Ray acoustic modeling of the surface fields of a submerged elastic
cylindrical shell with hemispherical endcaps.

**Jin-Meng Ho
**

**
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*SFA, Inc., 1401 McCormick Dr., Landover, MD 20785 and Naval Res. Lab.,
Washington, DC 20375
*

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Combining the available ray acoustic algorithms descriptive of submerged
thin cylindrical and spherical shells, this paper formulates the pressure and
velocity distributions on a hemispherically capped cylindrical shell insonified
by an obliquely incident acoustic plane wave. As the first ray acoustic model
for a noncanonical shell geometry of considerable current interest, it neglects
wave coupling and diffraction due to curvature discontinuities at the junctures
as well as contributions from the leaky waves excited through the endcaps. This
might be justifiable, because the junctions are not sharp edges (i.e., the
normals are continuous) and because the cylinder under consideration is very
long compared to the radius. By matching the surface wave vector along the
joints, however, due account is taken of leaky wave propagation on, and
radiation from, the hemispheres. The total pressure or velocity---their ray
constituents are related to each other by appropriate impedances---on the
cylinder is then synthesized by a modified geometrical acoustics field, as
developed recently, and a supersonic membrane wave field that accounts for the
leaky surface rays successively reaching the observer along helical
trajectories and great circles on the cylinder and hemispheres, respectively.
Numerical implementation is also performed here. The results are compared with
the reference solution generated at NRL by a boundary element code. [Work
supported by ONR.]