Thermal Convection Modeling of Evolution of the Earth's Core

A 2D model of purely thermal convection of the Earth's liquid core, occurring against the background of secular planet cooling, is presented. The model includes thermal convection equations in the Boussinesq approximation taking into account the Coriolis force caused by the rotation of the Earth. Metallic iron with 0.9 wt % & Ncy; is chosen as the core material. According to the modeling results, large vortices are formed in the liquid core prior to crystallization; they are 2D analogues of Taylor columns which might have generated the early magnetic field of the Earth. The early crystallization stages are characterized by the chaotic and shapeless growth of the solid core. Continuing growth of the solid core results in rearrangement of the convection structure, decreasing its average velocity, but increasing the heat flow at the core-mantle boundary due to increased heat of crystallization. The solid core reaches its present size in 0.5 Ga. The averaged temperature profile of the current liquid core is drastically different from the adiabatic one.