This is a continuation of the Process Intensifier - Optimization with CFD: Part 1 paper.

Shear Rate Distribution

ACUSOLVE readily outputs the velocity gradient tensor from which the scalar magnitude of shear rates is well defined in continuum mechanics and can be determined, reported, and studied. Hence, shear rates can be studied for shear sensitive fluid rheologies directly and can be further extended for shear rate sensitive calculations and correlations for subjects such as droplet size distribution models which evaluate and correlate droplet sizes with respect to surface tension, the amount of shear deformation incurred, etc along with such subjects as the Weber number.

What is interesting is that the graphical display of this information is difficult since the difference in shear near (or practically on) the impeller blades is about 4-6 orders of magnitude in the bulk. Here is an example in CASE A.

25000 s-1

close up to impeller, only near the tips

2500 s-1

close up to impeller, mostly near the blade edge

250 s-1

baffle edges and under  the impeller in the discharge zone

25 s-1

from below looking up, along the tank bottom and bottom tank wall

Figure 22: Distribution of shear for Case A. The red areas show the location of shear rates that are higher than the value in the caption.

This sort of graphical illustrations doesn't really appear to be very helpful, and it is very hard to see where these zones are. For this reason we looked at Eddy Viscosity.

Continue with Eddy Viscosity     or     Go back to Results     or     Go back to the Title Page