A preliminary study of the effects of some flow parameters in the generation of poloidal and toroidal energies within a 3-D spherical thermal-convective system with variable viscosity |
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| Authors: | Albert T Hsui Woo-Sun Yang John R Baumgardner |
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| Institution: | (1) Department of Geology, University of Illinois at Urbana-Champaign, 245 NHB, 1301 W. Green Street, 61801 Urbana, IL, USA;(2) MS B216, Los Alamos National Laboratory, 87545 Los Alamos, NM, USA |
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| Abstract: | The effects of variable viscosity on flow dynamics within spherical shells are investigated using a finite-element thermal convection model, and preliminary result for cases with relatively low Rayleigh numbers and small viscosity contrasts are reported. These results demonstrate some general effects of viscosity variation on mantle dynamics, and, in particular, the generation of toroidal energy. Since lateral viscosity variations are necessary in the generation of toroidal motion in a thermally driven convective system, it is not surprising our results show that flows with greater viscosity contrasts produce greater amounts of toroidal energy. Our preliminary study further shows that solutions become more time-dependent as viscosity contrasts increase. Increasing the Rayleigh number is also found to increase the magnitude of toroidal energy. Internal heating, on the other hand, appears to lead to less toroidal energy compared wth bottom heating because it tends to produce a thermally more uniform interior and thus smaller viscosity variations. |
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| Keywords: | Poloidal and toroidal energies thermal convection variable viscosity |
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