High-frequency acoustic properties of a fluid/porous solid interface. I. New surface mode

Abstract

We use Biot’s theory to search numerically for the velocities of the various surface waves, both the true slow surface wave and the pseudosurface waves, at an interface between a fluid half-space and a half-space of a fluid-saturated porous medium. We focus on the high-frequency range where the Biot–Plona slow wave is propagatory. We find that for an open-pore surface situation, the true surface mode exists for a limited range of material parameters and changes continuously into a slightly leaky pseudo-Stoneley mode as the mode speed increases past the slowest bulk wave speed; for the sealed pore situation there exist simultaneously a true surface mode (for all values of material parameters) and a pseudo-Stoneley mode. The pseudo-Rayleigh mode has features similar to those of the pseudo-Rayleigh mode for a fluid/nonporous solid case.