Sound Speed and Attenuation in Multiphase Media

Abstract

This report discusses an investigation of the sound speed and attenuation in multiphase media, sandy and muddy sediments, that has shown that a simplified-Biot theory adequately predicts the sound speed and attenuation in sandy sediments with porosities of less than 65%. In addition for muddy sediments with porosities of greater than 70% mixture theory can describe the sound speed. This report discusses the experimental and theoretical basis for these conclusions and related this investigation to other contemporary ONR sponsored research projects. A key finding is the conclusion that in waveguides with a sandy boundary that the effective attenuation obeys a power law with an exponent of 1.8 as proposed by Rosenfeld (2001) and Holmes (2007). Theory predicted a quadratic dependence, exponent of 2. This research has shown that energy removed by shear wave conversion explains this difference, that is the exponent of 1.8 compared to 2. Finally a card house theory was developed to explain the properties of high porosity muddy sediments and that a Mallock-Wood mixture equation describes the slow sound speed.

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Document Details

Document Type
Technical Report
Publication Date
Mar 15, 2012
Accession Number
ADA558268

Entities

People

  • William M. Carey

Organizations

  • Boston University

Tags

Communities of Interest

  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Acoustic Waves
  • Acoustics
  • Attenuation
  • Boundaries
  • Conversion
  • Elastic Waves
  • Equations
  • Frequency
  • Losses
  • Measurement
  • Porosity
  • Secondary Waves
  • Sediments
  • Sound Transmission
  • Transmission Loss
  • Waveguides
  • Waves

Readers

  • Acoustical Oceanography.
  • Systems Analysis and Design
  • Wave Propagation and Nonlinear Chaotic Dynamics.