Abstract:
The breathing mode for a gas-filled, spherical cavity in a saturated, poroelastic sediment is investigated. The analysis entails the scattering of an incident displacement field that preferentially excites the monopole resonance of the cavity. The main result demonstrates that a gas-filled, spherical cavity in a saturated poroelastic medium exhibits two distinct breathing mode resonances. These resonances arise from the two distinct longitudinal modes of propagation in saturated poroelastic medium as described by Biot's theory. Preliminary results from laboratory measurements involving a synthetic sediment will be presented. The experiments utilize spherical glass beads (250--300 (mu)m) saturated with an immersion fluid whose optical index of refraction matches the corresponding index for the glass. [Work supported by ONR.]