In the present study a mixing index was proposed in order to characterize
mixing processes of non Newtonian fluids. The apparent viscosity in a
mixing tank equipped with helical ribbon impeller was computed using a
CFD package. The symmetry plane of the mixing tank was divided into
sixteen zones where an average apparent dimensionless viscosity was
calculated to each of these zones from which a mixing index was evaluated.
The mixing index showed to increase with impeller rotational speed,
impeller/tank diameter ratio and showed to be affected by the rheological
parameters of the agitated fluid. The computed data of the mixing index
were correlated as a function of impeller/tank diameter ratio, impeller
rotational speed and rheological parameters. The proposed correlation
deviated from computed data by a maximum deviation of ± 50%.