This image shows the flow pattern in a vessel agitated by a helical ribbon impeller. The helical ribbon pumps down at the wall. The fluid is viscous and the impeller Reynolds number is approximately 10. The color at the tank bottom shows the velocity magnitude. The next series of images shows an experimental visualization of viscous blending with a helical ribbon impeller.
Material is added at the surface, and gets pulled down and mixed throughout the vessel.
The flow is laminar, with a Reynolds number below 10.