  Using highly resolved direct numerical simulations we examine the statistical
properties of the local energy flux rate $\Pi_\ell(x)$ towards small scales for
three isotropic turbulent magnetohydrodynamic flows, which differ in strength
and structure of the magnetic field. We analyse the cascade process both in the
kinetic and magnetic energy, disentangling the different flux contributions to
the overall energy dynamics. The results show that the probability distribution
of the local energy flux develops long tails related to extreme events, similar
to the hydrodynamic case. The different terms of the energy flux display
different properties and show sensitivity on the type of the flow examined. We
further examine the joint pdf between the local energy flux and the gradients
of the involved fields. The results point out a correlation with the magnetic
field gradients, showing however a dispersion much stronger than what is
observed in hydrodynamic flows. Finally, it is also shown that the local energy
flux shows some dependence on the local amplitude of the magnetic field. The
present results have implications for subgrid scale models that we discuss.
