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Solid earth sciences
Liquid Sodium Models of the Earth’s Core
Adams M M, Stone D R, Zimmerman D S, Lathrop D P
Magnetic dynamos, Fluid experiments, Geodynamo, Magnetic induction, Zonal flows, Turbulence, Experimental fluid dynamos, Spherical Couette flow
Rendering of the 3 m experiment. The inner sphere and the outer spherical shell can be driven independently by their two respective motors (top). Liquid sodium serves as the working fluid for hydromagnetic experiments
Our understanding of the dynamics of the Earth’s core can be advanced by a combination of observation, experiments, and simulations. A crucial aspect of the core is the interplay between the flow of the conducting liquid and the magnetic field this flow sustains via dynamo action. This non-linear interaction, and the presence of turbulence in the flow, precludes direct numerical simulation of the system with realistic turbulence. Thus, in addition to simulations and observations (both seismological and geomagnetic), experiments can contribute insight into the core dynamics. Liquid sodium laboratory experiments can serve as models of the Earth’s core with the key ingredients of conducting fluid, turbulent flow, and overall rotation, and can also approximate the geometry of the core. By accessing regions of parameter space inaccessible to numerical studies, experiments can benchmark simulations and reveal phenomena relevant to the Earth’s core and other planetary cores. This review focuses on the particular contribution of liquid sodium spherical Couette devices to this subject matter.