Accession Number : ADA309108

Title :   Nonlinear Properties of In-Situ Sediment Gas Bubbles.

Descriptive Note : Final rept. 1 Oct 94-31 May 95,

Corporate Author : WASHINGTON UNIV SEATTLE APPLIED PHYSICS LAB

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

PDF Url : ADA309108

Report Date : 21 JUL 1995

Pagination or Media Count : 61

Abstract : A model for difference frequency backscatter from trapped bubbles in sandy sediments is developed. A nonlinear volume scattering coefficient is computed via a technique similar to that of Ostrovsky and Sutin ('Nonlinear sound scattering from subsurface bubble layers', in Natural Physical Sources of Underwater Sound, B. R. Kerman (ed.), 363-373 (1993)) which treats the case of bubbles surrounded by water. The Biot theory is incorporated to model the acoustics of sandy sediment. Biot fast and slow waves are included by modeling the pore fluid as a superposition of two acoustic fluids with effective densities that differ from the pore fluid's actual density and account for its confinement within sediment pores. The principle of acoustic reciprocity is employed to develop an expression for the backscattering strength.

Descriptors :   *GAS DYNAMICS, *BUBBLES, *ACOUSTIC SCATTERING, *UNDERWATER ACOUSTICS, *SEDIMENTS, TRAPPING(CHARGED PARTICLES), BACKSCATTERING, GEOACOUSTICS, NONLINEAR ANALYSIS, UNDERWATER SOUND, OCEAN BOTTOM SOILS, DIFFERENCE FREQUENCY.

Subject Categories : Acoustics
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE