PURPOSE: To dramatically illustrate laminar flow by "unmixing" two fluids.

DESCRIPTION: Glycerine forms a cylindrical shell between two plexiglass cylinders. The inner cylinder can be rotated, setting up a laminar flow in the glycerine. Using a long hypodermic syringe, blue dye is injected in a line in the glycerine midway between the two cylinders, as shown in the left photo. As the inner cylinder is rotated several turns, the dye "mixes" with the glycerine, as seen in the center photo. When the rotation is reversed, the dye "unmixes" and almost returns to its original state, as seen in the photo at the right.

SUGGESTIONS: Follow directions provided carefully for filling the syringe and making the line.

REFERENCES: (PIRA unavailable.)

EQUIPMENT: Unmixing apparatus, hypodermic syringe with dye mixture.

SETUP TIME: 5 min.

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