Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Wreathed
A woman hides in silt and sediment in this award-winning underwater photo by Lee Jongkee. The motion of her plunge sends water spinning downward, where it picks up particles from the ground. Slow to settle, the sediment forms an ethereal mask for the swimmer. See more of the 2023 Sony World Photography winners here. (Image…
Rocket-Like Supercooled Drops
Many droplets can self-propel, often through the Leidenfrost effect and evaporation. But now researchers have observed freezing droplets that self-propel, too. The discovery came when observing the freezing of supercooled water drops inside a vacuum chamber. The researchers kept losing track of drops that seemingly disappeared. Upon closer inspection, though, they found that the drops…
Submarine Volcano
This pale green plume signals the activities of Kaitoku, an underwater seamount near Japan. Periodic activity picked up there in August 2022 and continued into the new year. The rising plume likely consists of superheated acidic seawater mixed with particulates, sulfur, and rock fragments. Underwater volcanoes like this one are thought to account for up…
How Large Particles Get in Sea Spray
When bubbles burst at the ocean’s surface, they eject droplets that can carry high concentrations of contaminants like pollutants, viruses, and microplastics. Previous theories posited that only particles smaller than the microlayer surrounding the bubble could make their way into these drops, but new work shows otherwise. As bubbles rise to the surface, they carry…
Shaping the Earth Through Cataclysm
Though we often think of the Earth as changing slowly, some events are so catastrophic that they change the landscape irrevocably. Some 15,000 years ago, a massive lake covered what is now Missoula, Montana. Dammed in by a 2,000-foot-tall wall of glacial ice, this lake contained more water than Lakes Ontario and Erie combined. But…
Paddling Pathlines
Rainbow lines cut through the darkness in photographer Stephen Orlando’s images of a kayak in motion. Equipped with an LED-lined paddle, Olympic kayaker Adam van Koeverden paddled along the waterfront while Orlando took long exposure photographs. The kayak’s motion makes it effectively invisible, while the paddle’s lights trace out the path of each stroke taken.…
Instabilities on Instabilities
The world of fluid instabilities is a rich one. Combine fluids with differing viscosities, densities, or flow speeds and they’ll often break down in picturesque and predictable manners. Here, researchers explore the Rayleigh-Taylor instability (RTI), which occurs when a denser fluid sits above a less dense one (in a gravitational field). It’s an extremely common…
Surfactants and Waves
In the ocean, waves often curl over and trap air, becoming plunging breakers. How do surfactants like soap or oil affect this process? That’s the question behind this video, where researchers visualize breaking waves with differing amounts of added surfactant. In the case of pure water, the wave forms a smooth jet that curls over…
Möbius-Like Liquid Crystals
Möbius strips are nonintuitive objects. They appear multi-dimensional but are single-sided. Such topologies show up in other systems, too. Here we see a liquid crystal where molecular alignments, along with vortices in the fluid, result in tiny, three-dimensional shapes nicknamed “möbiusons,” thanks to their unusual properties. Each one is about 10 μm long. The researchers…
Sedimentation After Flooding
The new year brought California a series of atmospheric rivers that poured record amounts of water onto drought-stricken lands. While the precipitation refreshed snowpacks and reservoirs, much of it washed away as soils oversaturated. Those flows carried sediment with them, creating swirls of brown and green along the coastline. Compare the two satellite images above…