Acoustic color of elastic objects near boundaries: High-fidelity, high-speed, 3-D finite-element modeling.

Abstract

NSWC PCD has developed a computer simulation system for modeling the acoustic color (target strength versus frequency and aspect angle) of realistic 3-D objects that are near to or straddling the interfaces between different fluids. It employs high-fidelity finite-element modeling of acoustic scattering from elastic objects (fully 3-D physics throughout object and environment), implemented in a custom-designed, scalable-architecture, multiblade rack system that efficiently manages the modeling of different parts of the frequency spectrum. The system automatically runs hundreds of thousands of finite-element models, dynamically changing the mesh resolution and outer fluid boundaries of the models as they sweep over frequency, and it produces a variety of outputs, the principal one being an acoustic color contour plot. This paper will begin with a brief overview of the acoustic color simulation system, followed by the results of two experimental validations of the system: (1) scattering from an aluminum cylinder in free space, and (2) scattering from an aluminum cylinder straddling the interface between two different fluids. The simulated acoustic color results will be compared with experimental, numerical, and theoretical results presented in other papers in this session. [Work supported by ONR and SERDP.]