The hydrodynamic performance of three mixers (single shaft central mixer (SSC)

single shaft off-centred mixer (SSO)

dual shaft off-centred mixer (DSO)

was investigated in the mixing of yield-pseudoplastic fluids (xanthan gum solutions) in the laminar regime. To explore and determine the efficiency of three mixers

both numerical and experimental approaches were adopted. The fluid rheology was described by the Herschel–Bulkley rheological model. Computational fluid dynamics was employed to simulate the apparent viscosity distribution

mixing time

and the flow pattern inside the stirred tank. The developed model was validated through experimentally measured torque. The influence mechanism of the rotational speed and fluid rheology on the cavern evolution was explored deeply. The performances of three mixers in this work were compared at the constant power input and fluid rheology with respect to the flow pattern

mixing time

and mixing efficiency. The results verify that the faster the rotating speed

the greater influence of the fluid rheology on the cavern evolution

and the more uniform apparent viscosity distribution. Moreover

the mixing time decreases continuously as the increasing power consumption per unit volume

and the dimensionless mixing time of DSO mixer was nearly 42.8% and 6.1% shorter than that of SSC and SCO mixer at the same Reynolds number

respectively. According to the mixing efficiency criteria

these data also revealed that DSO was more efficient than SSC and SSO.