A laminar dynamo driven by a steady pressure gradient
This animation describes the motion of a liquid metal down an infinite
helical pipe of rectangular cross-section, driven by a steady,
down-pipe pressure gradient. 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 3 panels show from left to right the cross-pipe field, the
down-pipe field and the down-pipe current alongside a time-trace of the
magnetic energy. The lower 3 panels show the cross-pipe flow, the
down-pipe flow and the downpipe vorticity alongside the kinetic energy.
For these parameters and geometry the solution is a-periodic. It
exhibits frequent reversals of the magnetic field direction.
Occasionally the field is quenched and reestablishes itself on the slow
time-scale of the kinematic eigenfunction.