“…The most important advantage of this technique is the knowledge of the rheological properties in situ, as, for example, measuring torque values and applying the effective viscosity concept (Metzner and Otto, 1957). This classical method has been generally used for predicting the power consumption during the mixing of non-Newtonian fluids with different geometries Espinosa-Solares et al, 1997;Tanguy et al, 1997;Aubin et al, 2000;Wang et al, 2000;Thibault and Tanguy, 2002). It is a well-known fact that the Metzner-Otto constant, K s , which express the proportionality existing between the effective shear rate and the stirrer speed, depends on impeller geometry.…”