Turbulent thermal convection in the Earth’s liquid core

Boussinesq approximation generalized to account for compressibility of the liquid core was used in direct numerical 3-D modeling of turbulent thermal convection in a spherical shell. The modeling employed Archimedes, Rosby, Reynolds and Peclet dimensionless numbers corresponding to Ar=10¹⁰, Ro=10^-7, Re=Pe=10⁶. Introducing in the model Reynolds and Peclet numbers, which were assumed 1 in the previous works allowed computations equivalent to significantly greater Rayleigh number up to Ra=10²². Modeling results indicate that ring-like structures orthogonal to the rotation axis are formed in the liquid core. In the rotating spherical shell these structures correspond to toroidal flow patterns which move in opposite directions. Averaged rotation velocity of the liquid core is characterized by oscillations similar to the observed oscillations of length of day (LOD).