Sound radiation by a baffled cylindrical shell: A numerical technique based on boundary integral equations, part 1

Abstract

A cylindrical thin elastic shell of finite length, extended by two semi-infinite perfectly reflecting cylinders, and immersed in a fluid extending up to infinity, is harmonically excited. By using the infinite fluid-loaded shell Green's tensor, the system of partial differential equations governing the shell displacement and the radiated sound pressure is reduced to a system of integral equations along the shell boundaries. By using the expansion of the unknown functions in Fourier series with respect to the angular variable of the natural cylindrical co-ordinates, the system of integral equations is reduced to an infinite set of systems of eight algebraic equations. The coefficients of the matrices and the second members of each system are given by Fourier integrals which are numerically evaluated and the accuracy of the computation can be fully controlled. Finally, each angular harmonic is computed with an accuracy of the same order as that of the Fourier integrals. The displacement is then obtained as a Fourier series; each of its coefficients U n is computed from the solution of an eighth order algebraic system.