A multi-stage industrial agitator system adapted to the mixing of a mixture whose viscosity varies during the process has beenudcharacterized by using CFD. In the entire study the mixture is supposed to have a Newtonian behavior even though it is rarely the case. Itudis shown that the well-adapted propeller is able to e7ciently blend high viscous media provided the Reynolds number is not too low. Audscale-up study of the agitated system has also been carried out by respecting the classical scale-up rules such as the geometrical similarityudand the conservation of the power per volume in the particular case of viscous media.udUsing an Eulerian approach, the hydrodynamics of three di9erent scales with geometrical similarity have been numerically characterizedudby the energy curve (power number versus Reynolds number) and by the Metzner and Otto constant in which both are required forudscale-up procedure. Experimental power measurements have been carried out at the smaller scale so that simulations have been partiallyudvalidated. New hydrodynamic criteria have also been introduced in order to quantify the =ows in the case of a multi-stage stirrer runningudat low Reynolds number. It has been shown how this hydrodynamic di9ers dramatically from one scale to another when scale-up atudconstant energy per volume is applied. From the CFD results, recommendations about the widely used scale-up rules have been suggestedudand modi>cations of stirring geometry have been proposed in order to reduce the =ow pattern variations during scale-up.ud? 2002 Elsevier Science Ltd. All rights reserved.
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