### ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

## 1aPA4. Scattering from a fluid-loaded elastic spherical shell in proximity
to a rough fluid--elastic interface: Numerical results.

**Judy Smith
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Garner C. Bishop
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*Nav. Undersea Warfare Ctr. Div., Newport, RI 02841-5047
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A null field T-matrix formalism is developed and used to calculate
scattering of a pressure wave from a fluid-loaded elastic spherical shell in
proximity to a rough fluid--elastic interface. The Helmholtz--Kirchhoff
integral representations of the various scattered pressure and displacement
fields are constructed. The surface fields are required to satisfy the elastic
boundary conditions and the scattered fields are required to satisfy the
extended boundary condition. The free-field T matrices for the elastic shell
and the rough fluid--elastic interface are constructed and used in the
Helmholtz--Kirchhoff and the null field equations for the shell-interface
system. It is shown that the T matrix for the system is simply related to the
free-field T matrices for the shell and the rough fluid--elastic interface. A
perturbative solution is obtained for scattering from arbitrary roughness, and
an ``exact'' solution is obtained for scattering from periodic roughness. The
``exact'' solution is used to obtain a variety of numerical results that show
some of the effects of the acoustic coupling that occurs between the rough
interface and the elastic spherical shell.