SCATTERING BY A HYBRID ASYMPTOTIC FINITE ELEMENT METHOD/

We describe a hybrid asymptotic/finite element method with application to the solution of the Helmholtz equation for large wavenumber. Thus, this method is suitable to compute the acoustic field radiated or sca ttered by acoustically large objects. The method is based on patching a short wavelength asymptotic expansion of the 'outer' field to an FEM interpolation of the 'inner' field. The patching takes place on an ar tificial boundary. Continuity of the field and its normal derivative a cross the artificial boundary is enforced weakly in a variational sett ing. The variational principle is described, as is an element-like imp lementation strategy. Two example applications are included: diffracti on by a truncated wedge and radiation by a source on a wave bearing su rface. (C) 1998 Elsevier Science S.A. All rights reserved.