Propagation of elastic waves in a fluid-filled cylindrical cavity located in a poroelastic medium: The influence of surface tension

In this work, synthetic waveforms generated by a point source of acoustic oscillations in a cylindrical cavity filled with a fluid are calculated using Biot's theory. The calculations are performed for the case when the pores and the cavity are filled with different immiscible fluids. The influence of surface tension on the parameters of elastic waves is investigated. It is shown that the influence of the effects associated with the presence of the surface tension is significant in the low frequency range (k(f) R) < 1, where k(f) is the wave number of the longitudinal wave in the fluid; R is the cavity radius. The influence of capillary effects on the velocity and attenuation of the low-frequency zeroorder normal mode (i. e., the Stoneley wave) has been studied. It is shown that the velocity and attenuation of this wave depend significantly on the surface tension at the boundary between the porous medium and the cavity. Our results show that the influence of capillary forces on kinematic and dynamic parameters of the zero-order normal mode increases with decreasing signal frequency.