Accession Number : ADA319310

Title :   New Multiple Scatter Model of the Ocean Sediment.

Descriptive Note : Final rept. 1 Jan-31 Aug 95,

Corporate Author : TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS

Personal Author(s) : Yelton, Dennis J. ; Stern, Morris ; Chotiros, Nicholas P.

PDF Url : ADA319310

Report Date : 15 SEP 1995

Pagination or Media Count : 66

Abstract : The reflection and scattering properties of an in homogeneous 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 grain size. The thickness of each layer was related to the associated grain size and porosity by a conservation of mass relationship. Lateral variations in grain size 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 grain size distribution were chosen to match existing experimental data so that the model could be tested. 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 500 kHz and 1 MHz normally incident plane waves. Coherent and random components of the reflected signal were calculated. The coherent part was directly related to the reflection coefficient. The random component was related to the scattering strength of the medium. It was found to increase with the mean grain size diameter, consistent with previous experimental results.

Descriptors :   *ACOUSTIC SCATTERING, *SEDIMENTS, COMPUTERIZED SIMULATION, ACOUSTIC WAVES, VISCOELASTICITY, SAND, BACKSCATTERING, POROSITY, SOUND TRANSMISSION, ACOUSTIC ATTENUATION, UNDERWATER ACOUSTICS, STRATIFICATION, OCEAN MODELS, PLANE WAVES, ACOUSTIC REFLECTION, UNDERWATER SOUND SIGNALS, BULK MODULUS.

Subject Categories : Acoustics
      Physical and Dynamic Oceanography

Distribution Statement : APPROVED FOR PUBLIC RELEASE