A laminar dynamo driven by a steady pressure gradient
This animation portrays a dynamo generated by the motion of liquid metal up and down two iinterwoven, infinite helical pipes of rectangular
Magnetic field is spontaneously created by
the initially steady pipe flow. The field
grows exponentially until it reacts back upon the flow
and elaborate time-dependent interactions ensue.
The top 4 panels show from left to right, in a cross-sections of one of the pipes, the cross-pipe field, the
down-pipe field, the down-pipe current and the rate of working of the
Lorentz force alongside a time-trace of the
magnetic energy. The lower 3 panels show the cross-pipe flow, the
down-pipe flow and the down-pipe vorticity alongside the kinetic energy.
For these parameters (R_m=8000, R_e=27) and geometry the nonlinear solution is a-periodic and highly
energetic. In this brief excerpt the
mean magnetic energy is considerably larger than the kinetic. The
formation of small-scale structures is marked.