Start your week with this mind-blowing demonstration of laminar flow, courtesy of the University of New Mexico's Physics Department. The apparatus, called a "Couette Cell," was developed by John DeMoss and Dr. Kevin Cahill, and uses dyed corn syrup to demonstrate how a fluid with a sufficiently low Reynolds number will flow along distinct paths in parallel layers (like fanning a deck of cards), thereby preventing disruption of the fluid. What is the Reynolds number, you ask?
The Reynolds number, R, is the dimensionless combination:
in which ρ is the density, ν the speed of the fluid, R the size of the flow, and η the viscosity.
Pretty straight forward, right? For those of you who haven't had the
misfortune awesome experience of being enrolled in a fluid dynamics course, here's the take-home message: the demonstration uses corn syrup because the Reynolds number is inversely related to viscosity, η. Corn syrup has a viscosity 5,000 times that of water. This property drives the Reynolds number below one, allowing for an extreme form of laminar flow called "Stokes flow," wherein the effects of friction become much greater than the forces of inertia. Translation? The fluid, despite appearances, will NOT blend (at least not in the way we're used to seeing fluids blend), and can be returned to its initial state by simply reversing the direction of mixing, as demonstrated by the colored droplets which return to their initial states.
Still confused? Try watching again after a second cup of coffee.