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In this paper, the hydrodynamic characteristics of stirred tanks equipped with a mono and double screws with both classic and modified profiles have been numerically investigated. The computer simulations are conducted within a computational fluid dynamic (CFD) code, based on resolution of the Navier-Stokes equations with a finite volume discretization. The numerical results showed that the velocity field is more efficient with the modified screw profile than the one with a simple profile. In the case of the double screw, the importance of viscous dissipation and pumping has been assessed. Also, the pumping and the energetic efficiency reach the highest values. The good agreement between the numerical results and the experimental data confirm the validity of the analysis method. [ABSTRACT FROM AUTHOR]

This paper presents the optimization of functional tolerancing by dispersions method, this later has made this evidence in manufacturing dimensions optimization. In this work the dispersions method on the basis of unknown variables is combined with the minimal transfer method for automatically the modelling of the functional requirements of a mechanical assembly. The simulation is constructed around two procedures. The first procedure executes the extraction of the functional requirements, the second procedure results in the optimization of the dispersions. The functional dimensions are synthesized by uses of the optimised values of the dispersions to compute the mean values and tolerances of the functional dimensions in the chains. They are in adequacy with the writing within the meaning of the ISO standard of the functional dimensions. [ABSTRACT FROM AUTHOR]