Inertial effects on thermochemically driven convection and hydromagnetic dynamos in a spherical shell

0486294 - GFÚ 2019 RIV GB eng J - Článek v odborném periodiku
Šimkanin, Ján - Kyselica, Juraj - Guba, P.
Inertial effects on thermochemically driven convection and hydromagnetic dynamos in a spherical shell.
Geophysical Journal International. Roč. 212, č. 3 (2018), s. 2194-2205. ISSN 0956-540X. E-ISSN 1365-246X
Grant CEP: GA MŠMT(CZ) LG13042
Institucionální podpora: RVO:67985530
Klíčová slova: composition and structure of the core * dynamo * nonlinear differential equations * numerical modelling
Obor OECD: Physical geography
Impakt faktor: 2.777, rok: 2018

We investigate the thermochemical convection and hydromagnetic dynamos in a spherical shell using the so-called codensity formulation with different buoyancy sources: the secular cooling from the mantle, the buoyancy sources due to the solidification at the inner core boundary and the combination of the two sources. Numerical simulations of the fully non-linear problem are performed using the PARODY code. In the thermochemical regime, we find that when the Prandtl numbers are lower than Ekman numbers, inertial convection is preferred, while the large-scale columnar convection is preferred otherwise. Unlike the large-scale convection, the inertial convection is found to be almost independent of the nature of driving buoyancy source. Moreover, the codensity field evolves to a new, radially symmetric stationary state. At the Ekman numbers much smaller than the Prandtl numbers, we have obtained the westward equatorial zonal flow in the chemically driven regime, while for the other cases zonal flows are eastward near the equator. In the dynamo regime, inertial convection is preferred when the Prandtl numbers are lower than Ekman numbers and the generated dipolar magnetic fields oscillate from the polar region to the mid-latitudes and back. In this case, the generated magnetic fields are independent of the type of buoyancy source. At the Prandtl numbers greater than Ekman numbers, both dipolar and hemispherical dynamos are found.
Trvalý link: http://hdl.handle.net/11104/0281154