Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
The Froghopper’s Incredible Suction
The tiny froghopper feeds on the sap in xylem, a feat that requires overcoming more than a megapascal of negative pressure. Plants, as you may recall, transport water and nutrients from their roots to their leaves through negative pressure, essentially pulling on the water as if it were a rope. So drinking that sap is…
“Starlit”
In “Starlit” filmmaker Roman De Giuli explores a universe in a fish tank. The planets and asteroids we see are droplets of paint and ink floating in a transparent, gel-like medium. I particularly like the sequences where paint stretches, beads up, and breaks into a string of droplets! (Image and video credit: R. De Giuli)
Fun From the Beach
Here’s a neat bit of fluid dynamics derived from a day at the beach! Our experiment begins with well-mixed (and likely compacted) sand grains and sea water in a bottle. When flipped, the sand layer sits at the top of the bottle with the water layer beneath. Very quickly new layers establish themselves in the…
Adhering Through Vibration
This little robot relies on vibration to generate its adhesion. By vibrating its flexible disk, it generates low pressure in the thin air layer between the disk and the surface. The force created is strong in the normal direction — meaning that the robot won’t come off the surface, even when carrying large weights —…
Jupiter in Many Lights
Sometimes the key to unraveling a mystery is to observe the phenomenon in different ways. That’s why researchers are increasingly taking advantage of multiple instruments simultaneously observing targets like Jupiter. Here we see the gas giant in three different types of light: infrared, visible, and ultraviolet. Infrared bands reveal the hot and cold regions of…
Programmable Capillary Action
Capillary action combines the cohesive forces within a liquid and the adhesive forces between a liquid and solid to enable a liquid to fill narrow spaces, even against the force of gravity. To control capillary action, researchers are 3D-printing what they call “unit cells,” tiny structures that water and other liquids can climb. There’s no…
Aerial Sheep Flow
I may never get tired of drone videos of sheep herding. They are mesmerizing to watch and full of so many characteristics of flow. Like a compressible fluid, the herd squeezes together as it passes through a gate, then spreads and decreases density as it reaches the pasture. The sequence of sheep moving down the…
Digging Into Acoustic Levitation
Acoustic levitation is a fascinating phenomenon in which small objects, like the Styrofoam balls seen here, are levitated by a standing acoustic wave. In this image, a color schlieren system shows regions of increasing pressure with height (red) and decreasing pressure with height (green). The balls sit within the colored bands, indicating that they’re levitated…
Controlling Aerosols Onstage
Few industries saw more disruption from the pandemic than the performing arts. To help orchestras return to the concert hall in a way that keeps performers and audience members safe, researchers have simulated air flow and aerosols around musicians onstage. Some instruments — like the trumpet — are super-spreaders when it comes to aerosol production,…
How Sewers Work
One of the most important and underappreciated pieces of urban infrastructure is the sewage system. We rely on them to make our waste vanish, as if by magic. In reality, these systems are carefully engineered and built to be largely self-cleaning and future-proof. Gravity is the primary driver of the system, and engineers design the…