  We report direct numerical simulations of dynamo generation for flow
generated using a Taylor-Green forcing. We find that the bifurcation is
subcritical, and show its bifurcation diagram. We connect the associated
hysteretic behavior with hydrodynamics changes induced by the action of the
Lorentz force. We show the geometry of the dynamo magnetic field and discuss
how the dynamo transition can be induced when an external field is applied to
the flow.
