Boundary element method for acoustic scattering in fluid-fluidlike and fluid-solid problems

In this paper the application of the two dimensional boundary element method to the scattering of plane sound waves from an infinite cylinder in a fluid is presented. The acoustic equation of the wave motion in the barotropic, inviscid fluid is deduced from the linearized hydrodynamics equations and the linearized equation of state, while the wave motion inside the solid is described by two different models. Two sets of boundary integral equations are presented for modelling the interaction of fluid-fluidlike and fluid-solid problems. Several test examples are presented to demonstrate the accuracy of the proposed formulations. Comparison with available analytical results, as well as numerical results for different sizes and positions of the internal boundary are given. Far field coefficients and the results of the scattering cross section demonstrate the different behaviour of the two models and the influence of the internal boundary.