### ASA 124th Meeting New Orleans 1992 October

## 5aUW13. Numerical integral equation solution for scattering from a
one-dimensional penetrable fluid interface and a buried rigid cylinder.

**Daniel O. Ludwigsen
**

**
Dajun Tang
**

**
**
*Dept. of Appl. Ocean Phys. and Eng., Woods Hole Oceanographic Inst., Woods
Hole, MA 02543
*

*
*
Ocean bottom scattering problems involve contributions from both the
roughness of the seafloor and inhomogeneities within the sediment or buried
objects. Here, a numerical procedure has been developed to find an exact
solution for scattering from an infinitely long rigid cylinder buried beneath a
one-dimensional rough interface. In this model, the water--sediment interface
is a penetrable fluid boundary with the conditions that pressure and vertical
particle velocity are continuous. The cylinder surface is rigid, i.e., the
vertical particle velocity on the boundary is zero. A boundary integral
approach is used: the pressure field and its normal derivative on the rough
surface, and the pressure field on the cylinder surface, are determined, then
used to find the far-field scattered field. This method was previously used for
a pressure-release boundary condition [E. I. Thorsos, J. Acoust. Soc. Am. 83,
78--92 (1988)] and the penetrable boundary [E. I. Thorsos, J. Acoust. Soc. Am.
90, 2232(A) (1991)]. It is now developed for the combination of a penetrable
boundary and a rigid cylinder to validate possible approximation methods. As a
benefit of this formalism, the shape of the buried object may be readily varied
to model elliptical and perhaps other cylinder cross sections.