Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Tricking a Kettle
Electric kettles are designed to shut off when the water inside them boils. But what does that mean exactly? In this video, Steve Mould explores that question by trying to trick his kettles into boiling off ethanol, a liquid with a lower boiling temperature than water. Steve figures that, if a kettle is designed to…
Liquid Bridges
In 1893, Baron Armstrong demonstrated a peculiar phenomenon — a liquid bridge of water suspended between two beakers with a strong electric charge between them (Image 1). More than a century later, the details of the mechanism remain challenging to pin down thanks to the setup’s combination of electohydrodynamics, heat transfer (Image 2), evaporation, and…
“Heaven”
Wispy white cirrus clouds cover dark skies glittering with stars in Roman De Giuli’s “Heaven”. Or so it appears. In reality, these skyscapes are made with watercolors, ink, and acrylic paint. The vistas are gorgeous regardless of whether they’re driven by turbulent convection (as in the atmosphere) or the Marangoni effect (as in this video)!…
When Bubbles Don’t Die
In a pure liquid, most bubbles pop almost immediately. But with a simple ingredient — a little heat — bubbles can live almost indefinitely. The mechanism is revealed in this video when the researchers use an infrared camera to watch a bubble on a heated pool. The top of the bubble is cooler than the…
Schooling Relies on Vision
For fish, collective motions like schooling rely on a few mechanisms, including flow sensing and — as beautifully demonstrated in this experiment — vision. Researchers used an infrared camera to track fish motions both in light and dark conditions and compared how orderly the school of fish was in each. As expected, the school’s motion…
Morphing Particle Rafts
A layer of tiny glass beads sitting atop a pool of castor oil becomes a morphing surface in this video. Applying an electric field creates enough electrostatic force to draw the interface upward against the power of both gravity and surface tension. Moving the electric field — either by shifting the electrode or simply moving…
Turbulence in Flight
Eagles and other birds spend much of their lives in the turbulence of our atmospheric boundary layer. Some of their interactions with turbulence — like using topographical effects to aid their flight — are well-known, but much remains uncertain. One team of researchers looked at a tagged golden eagle’s flight data, compared with known wind…
Portraits of Flight
During lockdown, photographer Doris Mitsch turned her eyes to the sky and began capturing these mesmerizing composite images of animals in flight. Vultures, crows, starlings, gulls, and bats all feature in her series. Some images, like “Lockdown Vulture (Signature)”, feature a single bird’s movement over a minute. Others show entire flocks over extended periods. I…
Mushy Layers
In many geophysical and metallurgical processes, there is a stage with a porous layer of liquid-infused solid known as a mushy layer. Such layers form in sea ice, in cooling metals, and even in the depths of our mantle. Within the mushy layer, temperature, density, and concentration can vary dramatically from one location to another.…
Splashing on Spheres
The splash of a droplet is a surprisingly complex phenomenon, depending not only on the droplet’s characteristics but also the surrounding air pressure, the roughness and temperature of the impact surface, and the surface’s curvature. In this study, researchers investigated the effects of surface curvature on splashing, finding that it’s harder for a drop to…