  We present results of nonlinear numerical simulations of gravity wave driven
shear flow oscillations in the equatorial plane of the solar radiative
interior. These results show that many of the assumptions of quasi-linear
theory are not valid. When only two waves are forced (prograde and retrograde)
oscillatory mean flow is maintained; but critical layers often form and are
dynamically important. When a spectrum of waves is forced, the non-linear
wave-wave interactions are dynamically important, often acting to decrease the
maintenance of a mean flow. The (in)coherence of such wave-wave interactions
must be taken into account when describing wave driven mean flows.
