Impeller Modeling Strategies

In this section the diffeent impeller modeling strategies employed simulating the flow fields in stirred tanks are examined. 

The shaft, hub and disc of the Rushton turbine (see Fig. 7.16), excluding the impeller blades, are treated as solid volumes. For different impeller geometries (and in rare cases also for the Rushton turbine), the impeller region has been bounded by two surfaces, one horizontal and one vertical [73]. In order to reduce the computational efforts one may utilize symmetries in the problem so that only a part of the domain needs to be simulated, but the domain applied must still include at least one baffle. To determine appropriate boundary conditions for the impeller surface, experimental data are required. In fact the method relies on experimental data for each geometry and fluid in question. The need for such amounts of empirical information is the main limitation of the IBC method. Moreover, the reliability on the results of a simulation using the IBC method depends directly on the quality of the experimental data [10]. 

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In Chap. 7, a brief summary of the agitation and fluid mixing technology is given. The main emphasis is placed on examining the modem strategies used to model the momentum transfer from the impeller to the fluid. The methods are sketched and the basic equations are listed. A few model simulation examples are presented. 

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