Liquid-metal experiments on geophysical and astrophysical phenomena

Recent decades have seen enormous progress in the experimental investigation of fundamental processes that are relevant to geophysical and astrophysical fluid dynamics. Liquid metals have proven particularly suited for such studies, partly owing to their small Prandtl numbers that are comparable to those in planetary cores and stellar convection zones, partly owing to their high electrical conductivity that allows the study of various magnetohydrodynamic phenomena. After introducing the theoretical basics and the key dimensionless parameters, we discuss some of the most important liquid-metal experiments on Rayleigh–Bénard convection, Alfvén waves, magnetically triggered flow instabilities such as the magnetorotational and Tayler instability, and the dynamo effect. Finally, we summarize what has been learned so far from those recent experiments and what could be expected from future ones. The understanding of fluid flows and their interaction with magnetic fields in planetary and stellar cores or accretion disks represents a challenge for geophysical and astrophysical research. This Review covers recent liquid-metal experiments on the underlying processes, such as convection, Alfvén waves, the magnetorotational instability and the dynamo effect.