  For a three dimensional magnetohydrodynamic (MHD) plasma the dynamo action
with ABC flow as initial condition has been studied. The study delineates
crucial parameter that gives a transition from coherent nonlinear oscillation
to dynamo. Further, for both kinematic and dynamic models at magnetic Prandtl
number equal to unity the dynamo action is studied for driven ABC flows. The
magnetic resistivity has been chosen at a value where the fast dynamo occurs
and the growth rate shows no further variation with the change of magnetic
Reynold's number. The exponent of growth of magnetic energy increases,
indicating a faster dynamo, if a higher wave number is excited compared to the
one with a lower wave number. The result has been found to hold good for both
kinematic and externally forced dynamic dynamos where the backreaction of
magnetic field on the velocity field is no more negligible. In case of an
externally forced dynamic dynamo, the super Alfvenic flows have been found to
excite strong dynamos giving rise to the growth of magnetic energy of seven
orders of magnitude. The back-reaction of magnetic field on the velocity field
through Lorentz force term has been found to affect the dynamics of the
velocity field and in turn the dynamics of magnetic field, leading to a
saturation, when the dynamo action is very prominent.
