Experimental Dynamos and the Dynamics of Planetary Cores

Laboratory experiments using liquid metals and nonmetallic liquids reveal a rich set of dynamical processes active in Earth's core and in the cores of other terrestrial planets. These processes include thermochemical convection and a variety of instabilities driven by irregularities in rotation, such as precession, libration, and tides. The spectrum of fluid motions in these experiments ranges from turbulence and inertial wave motions at high frequencies to global-scale zonal flows at low frequencies, and they result from the interplay between buoyant forces, rotational effects, melting and solidification, magnetic fields, and the spherical geometry of the core. This review summarizes strengths and limitations of laboratory fluid experiments for modeling core dynamics, identifies the key physical parameters, and highlights recent advances in understanding the complex flows that control the evolution of the core. Special emphasis is given to ongoing efforts to develop self-sustaining fluid dynamos.