2023_programme: Salinity, force chains and creep in sand and mud
- Session: 06. Marine sediment acoustics
Organiser(s): Megan Ballard, Kevin Lee and Nick Chotiros
- Lecture: Salinity, force chains and creep in sand and mud [invited]
Paper ID: 1861
Author(s): Chotiros Nicholas
Presenter: Chotiros Nicholas
Abstract: A model is proposed that can account for the frequency dependence of attenuation in both sand and mud. It is based on the poro-elastic acoustic propagation theory, extended to include squirt flow, with a correction for the sparse porosity in muds, and modified with a generalization of the squirt flow process. Unlike mud in fresh water, which is a suspension, marine mud is a poro-elastic medium. Salinity is critical because it causes the clay particles to flocculate, forming an aggregate of larger particles with a significant water fraction within an elastic skeletal frame. The force chain concept is used to simplify the elastic frame model. The result is a simplified skeletal frame model that naturally couples into the Biot theory of porous media. For mud, it predicts an attenuation that increases linearly with frequency at low frequencies, which is overtaken by viscous attenuation that increases as the second power of frequency at high frequencies. A couple of changes in parameter values allows it to change and match the attenuation in sand that increases as the second power of frequency at low frequencies and continue to increase at a lower rate at high frequencies. Thus, the same model can track the frequency dependence of sound speed and attenuation in both sand and mud. [Work supported by ONR, Ocean Acoustics Program]
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- Corresponding author: Dr Nicholas Chotiros
Affiliation: The University of Texas at Austin
Country: United States
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