Various Mixing Experiments

The Colorful Fluid Mixing Gallery

This shows the vortices behind the blades of a Leeuwrik impeller, as visualized in a cavitation tunnel. The vortices are filled with water vapor.

This image shows the flow pattern in a tank agitated with a D-6 impeller ("Rushton" turbine). The vessel is illuminated with a number of thin light sheets with different colors.

Blend time experiments are often done to determine mixing time. One commonly used method is to add an acid or a base to a vessel filled with a solution with an indicator. This image is one of a series of snapshots showing turbulent mixing in a vessel equipped with a high efficiency impeller.

The following two images show mixing visualizations similar to the one above. However, here the flow is laminar. Under laminar flow conditions locally unmixed zones may exist, usually in the form of self-circulating "doughnut" shaped regions. Whereas the rest of the fluid may be well mixed in less than 10 minutes, these locally unmixed regions may take hours to disperse. The first image shows this phenomenon with a D-6 impeller; the second image shows this phenomenon with a system of multiple pitched blade turbines.

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Last Updated April 10, 1998 by André Bakker
© André Bakker 1998