### ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

## 5aSA1. An acoustic boundary element method using analytical/numerical
matching applied to a fluid loaded plate.

**Ronald J. Epstein
**

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Donald B. Bliss
**

**
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*Mech. Eng. and Mater. Sci., Duke Univ., Box 90300, Durham, NC 27708-90300
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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 two dimensions to calculate the radiated
acoustic field and the associated fluid loading. The problem utilizes
overlapping smoothed doublets, and local corrections to calculate the doublet
strength distribution along 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 doublets, 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 near field,
and cancels the local solution in the far field. 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.]