Kinematic alpha effect in the presence of a large-scale motion.

We investigate how the addition of a large-scale steady motion, either shear or uniform flow, modifies the magnetic transport properties of a family of chaotic velocity fields with different correlation times. We compute numerically the kinematic alpha effect that those flows give rise to and show that it is reduced by the presence of a large-scale motion parallel to the large-scale magnetic field, except under certain conditions when it can be slightly enhanced via resonances. The alpha effect is shown to depend on the nature of the large-scale motion and on the temporal characteristics of the chaotic flow. These results highlight the strong influence that a shear or a uniform flow can have on the turbulent transport of magnetic fields.