A scientist’s morning latte has led to a potential new way to minimize fuel spills.
Emilie Dressaire, a mechanical engineer at New York University’s Polytechnic School of Engineering, swings through a neighborhood coffee shop on her way to work. The coffee in the cup sloshes as she drives to the office, turning corners and hitting potholes — except when she orders lattes. On those mornings, she noticed, there is much less spillage.
The reason is the lattes’ foam, according to a report she and an associate published in the professional journal Physics of Fluids.
After realizing that her lattes were spilling less, Dressaire mentioned her observation to Alban Sauret, a friend at the French National Center for Scientific Research. He said he’d noticed something similar at his neighborhood bar: foamy beers tend to slosh less than flat beers when carried on a serving tray.
The two of them set out to document the effect. Using dishwashing detergent to create a layer of foam on vats of water, they rocked the vats back and forth while filming the resulting waves with high-speed cameras. They learned that the foam reduced the size of the waves nearly 90 percent. They gave the vats a jolt similar to hitting a pothole and got the same results.
Dressaire and Sauret think that the foam creates friction that absorbs the energy of a wave. They are continuing to research the phenomenon — does the size of the foam bubbles influence their effectiveness, for instance — in hopes of being able to apply it to reduce sloshing in oil tankers.
In the meantime, Dressaire can try writing off the cost of her lattes as a research expense. That’s a good deal, but not nearly as sweet as if Sauret can do the same thing with his beer. □