  We combine a DEM simulation with a stochastic process to model the movement
of spherical particles in a turbulent channel flow. With this model we
investigate the mixing properties of two species of particles flowing through
the channel. We find a linear increase of the mixing zone with the length of
the pipe. Flows at different Reynolds number are studied. Below a critical
Reynolds number at the Taylor microscale of around $R_{c} \approx 300$ the
mixing rate is strongly dependent on the Reynolds number. Above $R_{c}$ the
mixing rate stays nearly constant.
