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A thick pipe‐like heat‐transfer mechanism in the mantle: Nonlinear coupling between 3‐D convection and variable thermal conductivity
Author(s) -
Dubuffet Fabien,
Yuen David A.
Publication year - 2000
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/1999gl008338
Subject(s) - thermal conductivity , heat transfer , convection , rayleigh number , mechanics , thermal diffusivity , materials science , thermal conduction , thermodynamics , convective heat transfer , mantle convection , natural convection , mantle (geology) , nonlinear system , boundary layer , geophysics , physics , geology , paleontology , tectonics , quantum mechanics , subduction
We have investigated the dynamics and heat‐transfer of 3‐D mantle convection with a realistic temperature‐and pressure‐dependent conductivity in a constant viscosity medium. Variable thermal conductivity is found to stabilize greatly the interior flow and the boundary‐layer dynamics, as compared to constant conductivity solutions for Rayleigh number up to 5 × 10 5 . Due to the nonlinear interaction between variable conductivity and convective flow, a great deal of heat can be transported coherently through the mantle within thick pipe‐like structures with a radius of around 500km. These pipe‐like solutions can be understood from the intermediate asymptotic nature of the nonlinear heat diffusion equation. We suggest that these thick plume‐like structures in the lower mantle imaged recently by tomography may be a manifestation of this nonlinearity in the conductivity of the temperature equation.