ANALYTICAL NUMERICAL MATCHING FOR EFFICIENT CALCULATION OF SCATTERINGFROM CYLINDRICAL-SHELLS WITH LENGTHWISE CONSTRAINTS/

Structural discontinuities in highly coupled fluid-structure systems a re modeled by an approach called analytical/numerical matching (ANM). This method separates the low-resolution global influence of a discont inuity from the relatively high-resolution local effects. A continuous , smoothed replacement for a fundamental structural discontinuity is c onstructed so that the system is ;identically unchanged beyond a small smoothing region. Simultaneously, the precise local effect of smoothi ng the discontinuity is retained in analytical form. The smoothed prob lem is solved by numerical techniques, with rapid convergence and redu ced computational cost. The original discontinuous character is restor ed using the analytical expression for the local difference between th e smoothed and the original problems. ANM has been successfully applie d to two-dimensional cases of acoustic scattering from a thin, infinit ely long cylindrical shell, with multiple structural discontinuities. Local solutions for longitudinal Line discontinuities with radial, tan gential, and rotational constraints have been formulated using ANM. Li ne constrained scattering problems, as well as line driven problems, a re investigated. The ability of analytical/numerical matching to repla ce a discontinuous physical problem by a well behaved continuous one f or numerical evaluation, while ultimately retaining the original geome try and physical behavior, is illustrated. (C) 1998 Acoustical Society of America.