A BOUNDARY INTEGRAL FORMULATION FOR THIN-WALLED SHAPES OF REVOLUTION

Much of the recent literature on boundary elements has addressed the practical limitations of the method. One issue under current scrutiny appears to be the inapplicability of formulations based on the Helmholtz integral to free-flooded shapes characterized by kh 41, where k and h are the acoustic wavenumber and the object's cross-sectional thickness dimension. The present article develops and applies a modal boundary integral technique especially tailored to thin geometries of revolution. The problems chosen for its demonstration are cases of acoustic diffraction by an open-ended cylindrical duct containing a sound source, where the scattering wall's outer and inner surfaces are an infinitesimal distance apart, and are respectively rigid and either rigid or compliant. The study concludes that general shapes with kh < 1 or kh = 0 should be treatable by at least one established numerical approach, after some analytical reinterpretation. © 1990, Acoustical Society of America. All rights reserved.