Scale separated low viscosity dynamos and dissipation within the Earth's core.

ABSTRACT: The mechanism by which the Earth's magnetic field is generated is thought to be thermal convection in the metallic liquid iron core. Here we present results of a suite of self-consistent spherical shell computations with ultra-low viscosities that replicate this mechanism, but using diffusivities of momentum and magnetic field that are notably dissimilar from one another. This leads to significant scale separation between magnetic and velocity fields, the latter being dominated by small scales. We show a zeroth order balance between the azimuthally-averaged parts of the Coriolis and Lorentz forces at large scales, which occurs when the diffusivities of magnetic field and momentum differ so much, as in our model. Outside boundary layers, viscous forces have a magnitude that is about one tho

SUBMITTER: Sheyko A 

PROVIDER: S-EPMC6105638 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature