Acoustic radiation from a finite spherical source placed in fluid near a poroelastic sphere

摘要

Acoustic radiation from a finite spherical source, vibrating with an arbitrary, axisymmetric, time-harmonic surface velocity distribution, while immersed at an arbitrary point near a poroelastic sphere in an unbounded ideal fluid medium is analyzed in an exact manner. The formulation utilizes the appropriate wave-field expansions, along with the translational addition theorems for spherical wave functions in combination with the Biot classic model for the description of poroelastic material behavior, to develop a closed-form solution in form of infinite series. The prime objective is to investigate the dynamic poroelasticity effects on acoustic radiation and its associated field quantities. The analytical results are illustrated with a numerical example, in which the spherical source, excited in vibrational modes of zero-th or first order, is positioned near a water-saturated sandstone sphere. The basic acoustic field quantities such as the modal acoustic radiation impedance load on the source, the radiated far-field pressure directivity pattern, and the radial acoustic intensity distribution are evaluated and discussed for representative values of the parameters characterizing the system.