Acoustic diffraction by a pair of poroelastic cylinders

This study treats the interaction of a plane compressional sound wave with a cluster of two fluid-saturated porous elastic cylinders submerged in an unbounded acoustic medium. The novel features of Biot dynamic model for description of poroelastic material behaviour along with the appropriate wave field expansions, the pertinent boundary conditions, and the translational addition theorem for cylindrical wave functions are employed to develop a closed-form solution in the form of infinite series. The theoretical model was extended to consider the case of sound diffraction by a pair of absorbing cylinders with locally reacting or extended reaction boundaries. The analytical results are illustrated with numerical examples in which two identical air-saturated glass wool cylinders are insonified by a plane sound wave at end-on/broadside incidence. The most fundamental acoustic field quantity, namely, the scattering form function amplitude is evaluated and discussed for representative values of the parameters characterizing the system. The effects of incident wave frequency, angle of incidence, and proximity of the two cylinders are examined. Particular attention has been focused on multiple scattering interactions as well as the surface reaction modelling effects. Numerical comparison is made with the case of acoustic diffraction by a pair of absorbing cylinders with locally reacting or extended reaction boundaries. Limiting cases involving two rigid cylinders and also a pair of penetrable (fluid) cylinders are considered and good agreements with well-known solutions are established. (C) 2006 WILEYNCH Verlag GmbH & Co. KGaA, Weinheim.