Local/global methods for structural acoustic radiation and scattering

Abstract

Solving structural acoustic problems in the mid-frequency range is a challenging task. Computation is expensive due to the large well-coupled nature of the fluid-structure system. Discrete structural elements, e.g., ribs and stiffeners, cause localized discontinuities that require much greater resolution than would be otherwise warranted. Radiation and scattering problems having certain types of constraints exhibit great sensitivity to fine-scale convergence. Our purpose in this research is to devise analytical and numerical ways to recast such problems to be amenable to an efficient and accurate numerical solution. Analytical/Numerical Matching (ANM) decomposes a problem into local and global parts. Analysis methods extract the local discontinuities, replacing the original discrete influence of the inhomogeneity by smooth forces. A smoother computational problem can be solved efficiently, without loss of information. The method has been demonstrated for configurations of increasing complexity, and has become a useful tool for solving realistic problems. The ANM approach has been successfully applied to the modal/FEA structural-acoustics code sonax, providing a new capability to handle 3-D structural discontinuities. Future research on the application of ANM to other finite element structural-acoustic codes is outlined. An ongoing effort to develop a general theory of structural acoustic homogenization is also summarized.