Based on the standard κ-ε turbulence model in combination with both the granular Eulerian multiphase model and the sliding-grid（SG） technology in Fluent,the contour of absolute pressure,the vectors of water velocity and the volume fraction of pulp fibers were analyzed,and the instantaneous flow behaviors of the pulp in the dilution zone and the S-type discharger at the bottom of high-consistency pulp-bleaching tower were simulated.The results show that the discharger helps to achieve uniform and complete discharge due to its special shape,that the rotating speed,the viscosity,the density and the particle diameter all influence the discharging effect,especially the rotating speed,and that the simulated tangential,radial and axial velocities of water accord well with the data measured using a particle image velometer（PIV）,which means that the combination of granular Eulerian multiphase model and SG technology is effective in describing the flow fields in the discharger and its dilution zone.