COMPLEX WAVE-NUMBER DISPERSION ANALYSIS OF GALERKIN AND GALERKIN LEAST-SQUARES METHODS FOR FLUID-LOADED PLATES

The technique of complex wave-number dispersion analysis is used to examine the accuracy of discretized systems in the representation of wave propagation phenomena. This technique was applied to study finite element approximations to in vacuo and fluid-loaded plates considering discretizations of Kirchhoff and Reissner-Mindlin plate theories coupled to an acoustic medium. The allowed evanescent waves in the finite element approximation of the in vacuo plate are obtained and compared with theory. The finite element dispersion relation for the coupled plate-fluid system is derived. Results for the Galerkin structural approximation coupled to Galerkin and Galerkin least-squares (GLS) fluid formulations are presented. Quantitative errors are reported and the significance of these errors in view of an analytical solution to the problem is given.