Abstract
We analyzed the effect of a rotor-stator mixer's head geometry and rotor-stator clearance （0.5 to 2 mm） on the efficiency of dispersing coarse alumina aggregates （with a primary particle size of approximately 10 nm） in suspension. We examined the effects on the dispersion efficiency and focused on the shear rate near the surfaces of the rotor-stator, and performed a computational fluid dynamics （CFD） analysis using a turbulence model with a low Reynolds number. The measured dispersion values showed that the efficiency with which the aggregates were distributed changed with the mixing head geometry, but was not affected by the clearance. The results of the CFD simulation showed that the effect of the mixing head geometry and the clearance on the dispersion efficiency is related to the volume of those regions where the shear rate is high. These high shear rate regions were restricted to within approximately 50μm from the surfaces of the rotor and stator.
