Definition of viscosity
The transport properties of fluid materials (either solid or liquid) are determined by their viscosity, which defines the resistance of the material to fluid flow (i.e., how “runny” it is). Viscosity, η, describes the time dependence of material motion through the ratio of applied shear stress, σ, to strain rate, 
via
The Earth's liquid outer core will have a relatively low viscosity compared to that of the solid inner core, which deforms on a much longer timescale. In geophysics, the quantity η is referred to as the dynamic viscosity, which, when normalized by the density, ρ, is termed the kinematic viscosity, ν:
Viscosity is a quantity dependent on the properties of the fluid at a molecular level. Therefore, both the viscosities defined above may also be referred to as “molecular viscosity.” In the outer core, fluid motion occurs over a range of length scales from that at a molecular level to large‐scale motion with characteristic distances comparable with the...
This is a preview of subscription content, log in via an institution to check access.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Bibliography
Bloxham, J., 1988. Dynamics of angular momentum in the Earth's core. Annual Reviews in Earth and Planetary Science, 26: 501–517.
Bondi, H., and Lyttleton, R.A., 1948. On the dynamical theory of the rotation of the Earth. Proceedings of the Cambridge Philosophical Society, 44: 345–359.
Buffet, B.A., 1997. Geodynamic estimates of the viscosity of the Earth's inner core. Nature, 388: 571–573.
Dobson, D.P., Crichton, W.A., Vočadlo, L., Jones, A.P., Wang, Y., Uchida, T., Rivers, M., Sutton, S., and Brodholt, J., 2000. In situ measurement of viscosity of liquids in the Fe‐FeS system at high pressures and temperatures. American Mineralogist, 85: 1838–1842.
Dobson, D.P., Brodholt, J.P., Vočadlo, L., and Chrichton, W., 2001. Experimental verification of the Stokes‐Einstein relation in liquid Fe‐FeS at 5 GPa. Molecular Physics, 99: 773–777.
Dumberry, M., and Bloxham, J., 2002. Inner core tilt and polar motion. Geophysical Journal International, 151: 377–392.
Frost, H.J., and Ashby, M.F., 1982. Deformation Mechanism Maps. Oxford: Pergamon Press.
Jeffreys, H., 1959. The Earth, its Origin, History and Physical Constitution. Cambridge: Cambridge University Press.
Officer, C.B., 1986. A conceptual model of core dynamics and the Earth's magnetic field. Journal of Geophysics, 59: 89–97.
Poirier, J.P., 1988. Transport properties of liquid metals and viscosity of the Earth's core, Geophysical Journal International, 92: 99–105.
Poirier, J.P., 2002. Rheology: elasticity and viscosity at high pressure. In Hemley, R.J., Chiarotti, G.L., Bernasconi, M., and Ulivi, L. (eds.), Proceedings of the International School of Physics “Enrico Fermi”. Amsterdam: IOS Press. Course CXLVII.
Sato, R., and Espinosa, A.F., 1967. Dissipation factor of the torsional mode T2 for a homogeneous mantle Earth with a soft‐solid or viscous‐liquid core. Journal of Geophysical Research, 72: 1761–1767.
Secco, R.A., 1995. Viscosity of the outer core. In Ahrens, T.J. (ed.), Mineral Physics and Crystallography: A Handbook of Physical Constants, AGU Reference Shelf 2. Washington, D.C.: American Geophysical Union.
Verhoogen, J., 1974. Chandler wobble and viscosity in the Earth's core. Nature, 249: 334–335.
Vočadlo, L., Alfè, D., Price, G.D., and Gillan, M.J., 2000. First principles calculations on the diffusivity and viscosity of liquid Fe‐S at experimentally accessible conditions. Physics of the Earth and Planetary Interiors, 120: 145–152.
de Wijs, G.A., Kresse, G., Vočadlo, L., Dobson, D.P., Alfè, D., Gillan, M.J., and Price, G.D., 1998. The viscosity of liquid iron at the physical conditions of the Earth's core. Nature, 392: 805–807.
Won, I.J., and Kuo, J.T., 1973. Oscillation of the Earth's inner core and its relation to the generation of geomagnetic field. Journal of Geophysical Research, 78: 905–911.
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2007 Springer-Verlag
About this entry
Cite this entry
Vočadlo, L. (2007). Core Viscosity. In: Gubbins, D., Herrero-Bervera, E. (eds) Encyclopedia of Geomagnetism and Paleomagnetism. Springer, Dordrecht. https://doi.org/10.1007/978-1-4020-4423-6_42
Download citation
DOI: https://doi.org/10.1007/978-1-4020-4423-6_42
Publisher Name: Springer, Dordrecht
Print ISBN: 978-1-4020-3992-8
Online ISBN: 978-1-4020-4423-6
eBook Packages: Earth and Environmental ScienceReference Module Physical and Materials ScienceReference Module Earth and Environmental Sciences