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

2pSA9. Hybrid asymptotic-numerical method for evaluating diffraction coefficients.

Paul E. Barbone

Isaac Harari

Dept. of Aerospace & Mech. Eng., Boston Univ., Boston, MA 02215

, and Dept. of Solid Mechanics, Mater. and Structures, Tel-Aviv Univ., 69978 Ramat Aviv, Israel

In complicated structural acoustics problems, the lack of relevant diffraction coefficients often limits the applicability of the geometrical theory of diffraction. A hybrid asymptotic/finite-element method is described that lends itself to the numerical evaluation of diffraction coefficients. It is based on the method of asymptotic patching. The farfield asymptotic expansion of the scattered field is patched to a finite-element interpolation of the field near the point of diffraction. This idea leads to the definition of an asymptotically equivalent boundary-value problem, which is defined on a small domain and therefore is efficiently discretized. The method is demonstrated with an application to diffraction by an imperfect wedge. [Work supported by ONR.]