Accession Number : ADA296230

Title :   Bottom Backscatter from Trapped Bubbles - II.

Descriptive Note : Final rept. 15 Apr 93-15 Apr 94,

Corporate Author : TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS

Personal Author(s) : Boyle, Frank A. ; Chotiros, Nicholas P.

PDF Url : ADA296230

Report Date : 01 DEC 1994

Pagination or Media Count : 40

Abstract : A model for acoustic backscatter from trapped gas bubbles in sandy sediments was described in 'Bottom Backscatter from Trapped Bubbles'. In that model, trapped bubbles were assumed to scatter as if they were free bubbles in open water. In this report, the effects of bubble confinement in sediment pores on the resonance behavior of the bubble are accounted for. This is done by assigning the pore fluid an effective density that differs from its actual density, accounting for the fact that the fluid is partially confined within pores. The effective density is computed by way of the Biot theory. Two effective densities are specified, one for each of the two compressional waves that the Biot theory predicts. As a result, the medium has two scattering cross sections, which are both included in the resulting expression for scattering strength.

Descriptors :   *BUBBLES, *ACOUSTIC SCATTERING, SIZES(DIMENSIONS), SCATTERING CROSS SECTIONS, SAND, BACKSCATTERING, POROSITY, GASES, RESONANCE, CONFINEMENT(GENERAL), SEDIMENTS, OCEAN BOTTOM SOILS, TRAPS.

Subject Categories : Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE