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Numerical study of high Rayleigh number convection in a medium with depth-dependent viscosity

Gurnis, Michael and Davies, Geoffrey F. (1986) Numerical study of high Rayleigh number convection in a medium with depth-dependent viscosity. Geophysical Journal of the Royal Astronomical Society, 85 (3). pp. 523-541. ISSN 0016-8009. http://resolver.caltech.edu/CaltechAUTHORS:20130423-075303448

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Abstract

The equations of motion are solved numerically for a Boussinesq fluid with infinite Prandtl number in a square 2-D box where the viscosity increases with depth. Three heating modes are employed: bottom heating, internal heating, and half bottom and half internal heating. In all cases the boundaries are free slip. The range of Rayleigh numbers employed is 10^4-10^7. The viscosity increases as 10^(β(1-y)), where y is distance measured from the bottom upwards and β is a free parameter. In the bottom heated cases, the convective velocities slow near the bottom and result in a large temperature drop between the bottom boundary and interior compared with the top boundary and the interior. This results in increased buoyancy in the ascending limb. In the internally heated case, the flow in the top half of the box resembles Rayleigh-Bènard convection and in the bottom half it approaches a conductive thermal regime for β greater than about 2. In this case the top surface heat flux decays from ascending to descending limb and the ascending and descending limbs become more equal in their buoyancy. Increasing β decreases the efficiency of heat transport, but has little effect on the exponents of Nu-Ra and Pe-Ra relations. There is a larger decrease in heat transport efficiency for a given β in the bottom heated case compared to the internally heated case.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1111/j.1365-246X.1986.tb04530.xDOIArticle
Additional Information:© 1986 Wiley. Accepted 1985 October 19. Received 1985 May 8; in original form 1984 October 2. Article first published online: 2 Apr 2007.
Group:Seismological Laboratory
Subject Keywords:mantle convection; mantle viscosity
Record Number:CaltechAUTHORS:20130423-075303448
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20130423-075303448
Official Citation:Gurnis, M. and Davies, G. F. (1986), Numerical study of high Rayleigh number convection in a medium with depth-dependent viscosity. Geophysical Journal of the Royal Astronomical Society, 85: 523–542. doi: 10.1111/j.1365-246X.1986.tb04530.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:38072
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:23 Apr 2013 17:32
Last Modified:11 Jun 2015 12:59

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