Ultra-Laminar Reversible Flow Demo

Inspired by popular demos online, I created a low-cost, zero-tool demonstrator of an interesting concept in fluid dynamics: reversible flow between two concentric cylindrical surfaces created in extremely low Reynolds number conditions (high viscosity, low velocity).

When the crank is turned by a student, the inner drum rotates with a 1:2.5 gear ratio. The white background of the printed drum gives a great contrast to view drops of colored dye, which spread out when the drum rotates only to return to their initial positions when the drum is rotated back! I’m very proud that all the components are support-free and print in place on a hobby grade FDM machine.

I fabricated and assembled two copies of this design for the 2nd annual CU Early Engineering Exposure Fair hosted by the Mechanical Engineering department in the spring of 2023. Contact me for design files.