Radiation and scattering from large axisymmetric structures in an infinite or semiinfinite fluid medium

Abstract

A complex axisymmetric structure immersed in an infinite or semiinfinite fluid medium, excited by a plane acoustic wave or by a spherical or cylindrical acoustic wave emanating from a source in the vicinity of the structure or by a mechanical force acting on the structure, scatters and/or radiates the acoustic waves in the fluid medium. At a lower frequency range of excitation, vibrations of the structure and the radiating acoustic pressure strongly couples, whereas at higher frequency of excitation the structure can be regarded as rigid. A program called FIST (Fluid Interacting with STructures) is developed to analyze these problems. Using the Helmholtz integral, one can write a linear relation between the particle velocity normal to a cavity surface and the corresponding acoustic pressure. For efficiency and economy of calculations and for the consistency of velocity distribution between the structural elements and the corresponding fluid elements in contact, the distribution of pressure and velocity on...