  We study the evolution of an inflation-generated magnetic field, due to its
coupling to fluid motions, during cosmological phase transitions. We find that
the magnetic field stays almost unchanged on large scales, while on small
scales the spectrum is modified in such a way that power at small scales
becomes progressively suppressed. We also show that the magnetic field
generates turbulent motions in the initially turbulence-free plasma. On large
scales, the slope of the resulting kinetic energy spectrum is consistent with
that of white noise.
