ABSTRACT Visualization of flow patterns is an effective method for clarifying mixing mechanisms and determining optimal mixing conditions. When high‐ and low‐viscosity fluids were mixed, satisfactory mixing was relatively easy to achieve with large impellers. However, certain impellers produced unusual flow patterns because there was no gap between the impeller tip and the interface of the two fluids. When a large volume of high‐viscosity fluid was mixed with a small volume of low‐viscosity fluid, the helical ribbon impeller was effective. For the Rushton turbine, placing the impeller at the interface reduced the mixing time compared with placement in the high‐viscosity region.
Shudo et al. (Fri,) studied this question.