Fluid Dynamics Experiments on Core Formation

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The primary structure of Earth's interior -- the dense iron-rich metallic core surrounded by the less dense silicate and oxide mantle -- was established during planetary accretion, when the vast amounts of energy released by large impacts produced widespread melting, allowing the denser metals to segregate from the molten silicates and form the core. The purpose of this research is to quantify the fluid mechanical processes by which the core-forming metals partially mixed with and later segregated from the mantle-forming silicates in the early Earth. A series of laboratory fluid dynamical experiments will be made using silicone oils and sucrose solutions to model the molten silicates and liquid gallium and other dense fluids to model the core-forming metals in a magma ocean. The experiments will measure the turbulent exchange of heat and chemical tracers between the two fluids under gravitationally stable and unstable conditions, respectively. Important outcomes of this research are experimentally calibrated laws for turbulent heat and chemical exchange between liquid metals and non-metals. We intend to extrapolate our experimental results to the conditions of the early Earth, thereby placing constraints on the initial state of the deep interior, including the initial partitioning of heat and chemical species between the core and the mantle.