  Under the combined constraints of rapid rotation, sphericity, and magnetic
field, motions in planetary cores get organized in a peculiar way. Classical
hydrodynamic turbulence is not present, but turbulent motions can take place
under the action of the buoyancy and Laplace forces. Laboratory experiments,
such as the rotating spherical magnetic Couette DTS experiment in Grenoble,
help us understand what motions take place in planetary core conditions.
