  We have computed wind models with time-dependent dust formation and
grain-size dependent opacities, where (1) the problem is simplified by assuming
a fixed dust-grain size, and where (2) the radiation pressure efficiency is
approximated using grain sizes based on various means of the actual grain size
distribution. It is shown that in critical cases, the effect of grain sizes can
be significant. For well-developed winds, however, the effects on the mass-loss
rate and the wind speed are small.
