Abstract: Based on the gas-liquid interface morphology comparison， LDV test verification and CFX immersed solid model， a numerical study was conducted on the characteristics of internal flow field in a 1 L flocculation agitator by using the standard k-ε turbulence model. Results indicated that the velocity and its gradient are higher in the downward recirculating flow region， and the velocity gradient increases with the increase of stirring intensity. The rotational speed has larger influence on the tangential velocity gradient near the impeller， where the tangential velocity gradient is larger than that in other regions by two orders of magnitude. The turbulent dissipation rate， turbulent kinetic energy and eddy viscosity are higher in the downward circulation area. The rotational speed of impeller in the range of investigation has a larger impact on the turbulence kinetic energy， and a relatively small impact on the eddy viscosity.

Key words: flocculation agitator, flow field characteristics, numerical simulation, immersed solid model, velocity gradient