### ASA 130th Meeting - St. Louis, MO - 1995 Nov 27 .. Dec 01

## 2aSA2. An acoustic boundary element method using analytical/numerical
matching applied to a three-dimensional fluid-loaded plate.

**Ronald J. Epstein
**

**
Donald B. Bliss
**

**
**
*Dept. of Mech. Eng. and Mater. Sci., Duke Univ., Box 90300, Durham, NC
27708-90300
*

*
*
Analytical/numerical matching (ANM) is a hybrid scheme combining a
low-resolution global numerical solution with a high-resolution local analytical
solution to form a composite solution. ANM is applied to a harmonically
vibrating flat plate in three dimensions to calculate the radiated acoustic
field and the associated fluid loading. The problem utilizes overlapping
smoothed dipoles, and local corrections to calculate the dipole strength
distribution on the surface of the plate. A smoothing length scale is introduced
that is larger than the smallest physical scale, and smaller than the largest
physical scale. The global low-resolution solution is calculated numerically
using smoothed dipoles, and converges quickly. Local corrections are done with
high-resolution local analytical solutions. The global numerical solution is
asymptotically matched to the local analytical solutions via a matching
solution. The matching solution cancels the global solution in the nearfield,
and cancels the local solution in the farfield. The method is very robust,
offering an insensitivity to collocation point position. ANM provides
high-resolution calculations from low-resolution numerics with analytical
corrections, while avoiding the subtlety involving singular integral equations,
and their numerical implementation. [Work supported by ONR.]