Gravitational Differentiation in the Regimes from Stokes Settling to Rayleigh–Taylor Flows

Abstract

The Earth’s core was formed under gravitational differentiation in the process of the separation of iron and silicates. Most of the iron has gone into the core as early as during the growth of the Earth. However, iron continued to precipitate even during the subsequent period of partial solidification which developed from the bottom upwards. At the different stages and in the different layers of the mantle, iron was deposited in different regimes. This paper addresses the mechanisms of the deposition of a cloud of heavy interacting particles (or drops) in a viscous fluid. A new approach that makes it possible to analytically and numerically trace the changes in the structure of the flows in a two-component suspension under the continuous transition from the Stokes settling (for the case of a cloud of large particles) to the Rayleigh–Taylor flows and heavy diapirs (for the case of a cloud of small particles) is developed. It is numerically and analytically shown that the both regimes are different limiting cases of the sedimentation convection in suspensions.