Accession Number : ADA191643

Title :   Evaluation of the Biot Coefficients.

Descriptive Note : Final technical rept.,

Corporate Author : TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS

Personal Author(s) : Yavari, B ; Bedford, A

PDF Url : ADA191643

Report Date : Jan 1987

Pagination or Media Count : 30

Abstract : The Biot equations are the most promising approach for modeling the propagation of acoustic waves in ocean sediments. A method has been developed by Bedford, Costley and Stern for determining the drag and virtual mass coefficients in Biot's equations as functions of frequency. The method requires solving for the motion of the fluid in the pores when the pore walls are subjected to a spatially uniform, oscillatory motion. In this project, a finite element algorithm has been developed to determine the fluid motion. The accuracy of the model has been verified using a model problem for which exact results could be obtained. The drag and virtual mass coefficients have been determined for several two dimensional pore spaces. It has been determined that the drag coefficient is insensitive to the pore geometry while the virtual mass coefficient is very sensitive to the pore geometry. It has also been shown that the coefficients can be expressed in nondimensional forms which permit their values to be scaled for different values of a characteristic linear dimension of the pore space. This project has established a firm basis for proceeding to determine the coefficients for three dimensional pore spaces.

Descriptors :   *ACOUSTIC WAVES, *SEDIMENTS, *WAVE PROPAGATION, *UNDERWATER ACOUSTICS, ACCURACY, ALGORITHMS, COEFFICIENTS, DRAG, EQUATIONS, FINITE ELEMENT ANALYSIS, FLUIDS, MODELS, MOTION, OCEAN BOTTOM, OSCILLATION, SIZES(DIMENSIONS), ACOUSTIC VELOCITY, POROSITY, BOUNDARY VALUE PROBLEMS

Subject Categories : Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE