Efficient calculation of vibration and radiation from fluid-loaded structures with discontinuities using analytical-numerical matching

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 cause localized discontinuities that require much greater resolution than would be needed otherwise. Radiation and scattering problems having certain types of constraints exhibit great sensitivity to fine-scale convergence. This research demonstrates a novel way to recast such problems in order to efficiently and accurately solve numerically. 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 and resulting in a much smoother computational problem. The method has been demonstrated 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. Excellent results have been obtained for the efficient calculation of surface motion and radiated sound for a fluid loaded shell driven at a localized structural attachment.