In this work, the pulp flow behaviour for the dilution-zone of two rotary dischargers, that is, S-type and straight-type discharger, were simulated by computational fluid dynamics (CFD). The time-accurate transient simulations of two rotary dischargers were based on the standard k-epsilon turbulence model in conjunction with the granular Eulerian multiphase model and Sliding-grid (SG) algorithm technique in FLUENT, so that the key parameters for evaluating the discharger performance, that is, the volume fraction of pulp, vectors of instantaneous water velocity, and turbulent kinetic energy of water in the given systems were calculated. The results from the simulations proved that the S-type discharger was better than the straight one in pulp mixing and discharging. For the given S-type discharger system, a higher revolution speed would lead to a smaller volume fraction thus makes pulp discharging much easier. The comparison results of the experiment data measured by particle image velocimetry (PIV) and CFD simulations verified that Eulerian and standard k-epsilon turbulence models could provide a better description for the flow patterns in the dilution-zone.