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Anomalous Bulk Viscosity of Two-Phase Fluids and Implications for Planetary Interiors

Stevenson, D. J. (1983) Anomalous Bulk Viscosity of Two-Phase Fluids and Implications for Planetary Interiors. Journal of Geophysical Research B, 88 (B3). pp. 2445-2455. ISSN 0148-0227. https://resolver.caltech.edu/CaltechAUTHORS:20140311-155158640

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Abstract

A calculation is presented for the irreversible entropy production that accompanies the imposition of a pressure perturbation on a two-phase medium consisting of a dilute suspension of one phase (as droplets or snowflakes) in another (liquid) phase of significantly different composition. No metastability is allowed, and the relaxation process is then dominated by the finite diffusivity of solute. The fluid medium behaves as though it has a very large bulk viscosity (typical value ∼10^(12) P in the low-frequency limit). The minimum quality factor Q for acoustic or tidal pressure oscillations is found to be typically ∼10^2–10^3 and occurs at a frequency ω_0 ∼ 4πDηS where D is the solute diffusivity and η is the number density of suspended inclusions of average radius S. For plausible parameter values, ω_0 is in the range of planetary interest (e.g. 10^(−4) Hz). At ω ≲ ω_0, Q ∝ ω^(−l); at ω_0 ≲ ω ≲ Ds^(−2), Q ∝ ω; and at ω ≳ Ds^(−2), Q ∝ ω^(½). The model is applied to helium rain clouds in the deep interiors of giant planets and is found to be capable in principle of providing a tidal Q ∼ 10^5, needed to explain the volcanism of Io and resurfacing of Enceladus. The model is also applied to the earth's outer core and found to be marginally capable of explaining the attenuation of radial modes (notably _oS_o) and potentially capable of providing significant attenuation of earth tides. However, quantification and application of the model are difficult because of large uncertainties in the nature of the required two-phase suspensions.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://onlinelibrary.wiley.com/doi/10.1029/JB088iB03p02445/abstractPublisherArticle
http://dx.doi.org/10.1029/JB088iB03p02445DOIArticle
ORCID:
AuthorORCID
Stevenson, D. J.0000-0001-9432-7159
Additional Information:© 1983 American Geophysical Union. Received July 12, 1982; accepted October 15, 1982. I wish to especially thank H. Houben (NASA Ames) for his careful review of the manuscript, resulting in a complete rewriting of the appendix. This work is supported by NASA grant NAGW-185 and NSF grant EAR-8206383 and is contribution 3800 from the Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125. Paper number 2B1617.
Funders:
Funding AgencyGrant Number
NASANAGW-185
NSFEAR-8206383
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Caltech Division of Geological and Planetary Sciences 3800
Issue or Number:B3
Record Number:CaltechAUTHORS:20140311-155158640
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20140311-155158640
Official Citation:Stevenson, D. J. (1983), Anomalous bulk viscosity of two-phase fluids and implications for planetary interiors, J. Geophys. Res., 88(B3), 2445–2455, doi:10.1029/JB088iB03p02445.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:44267
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:12 Mar 2014 17:55
Last Modified:03 Oct 2019 06:16

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