2pUW11. Angular variation in the simulated reflection and scattering properties of granular poroelastic ocean sediments.

Session: Tuesday Afternoon, May 14

Time: 4:05

Author: Dennis J. Yelton
Author: Nicholas P. Chotiros
Location: Appl. Res. Labs., Univ. of Texas, Austin, TX 78713-8029


Reflection and scattering properties of an inhomogeneous poroelastic medium were studied via numerical simulation. The inhomogeneous medium was modeled as an ensemble average of randomly layered poroelastic material. Each layer represented a granular material of a particular grainsize. The thickness of each layer was related to the associated grainsize and porosity by a conservation of mass relationship. Lateral variations in grainsize were approximated by performing a coherent ensemble average of results from several realizations of the randomly stratified medium. Poroelastic medium parameters were chosen to represent water-saturated sand. The mean and standard deviation of the grainsize distribution were chosen to match existing experimental data in order to test the model. Specifically, the inhomogeneous medium was modeled as bounded by a homogeneous water half-space on the source side, and a homogeneous poroelastic half-space of equivalent average porosity on the other side. Reflected signals were computed for high-frequency plane waves incident at various grazing angles. Coherent and random components of the reflected signal were calculated. The coherent part was related to the reflection coefficient. The random component was related to the scattering strength of the medium. Results were compared with existing experimental data. [Work supported by ONR.]

from ASA 131st Meeting, Indianapolis, May 1996