Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
When Reservoirs Run Dry
With the ongoing megadrought in the U.S. Southwest, more and more reservoirs are reaching historic low water levels. So it’s worth asking: what happens when a reservoir runs dry? And what, exactly, does a reservoir do in the first place? In this Practical Engineering video, Grady tackles both questions and takes a look at the…
“Art of Paint”
Filmmaker Roman De Giuli is always coming up with spectacular and visually fascinating new ways to manipulate ink and other liquids. In “Art of Paint,” he applies thin layers atop a custom plate that can be tilted in any direction. The results sometimes resemble acrylic paint pours, sometimes Marangoni flows, and sometimes look more like…
Slow to Relax
Oobleck is a decidedly weird substance. Made from a dense suspension of cornstarch in water, oobleck is known for its mix of liquid-like and solid-like properties, depending on the force that’s applied. In a recent study, researchers took a look at what happens when you really push oobleck to the extreme. When the force applied…
The Tea Leaves Effect
If you’ve ever stirred a cup of tea with loose leaves in it, you’ve probably noticed that the leaves tend to swirl into the center of the cup in a kind of inverted whirlpool. At first, this behavior can seem counter-intuitive; after all, a spinning centrifuge causes denser components to fly to the outside. In…
Bubbles in Turbulence
In nature and industry, swarms of bubbles* often encounter turbulence in their surrounding fluid. To study this situation, researchers used numerical simulation to observe bubbles across a range of density, viscosity, and surface tension values relative to their surroundings. They found that density differences between the two fluids made negligible changes to the way bubbles…
Actinoform Clouds
Flower-shaped actinoform clouds, like those seen on the left side of this satellite image, were only discovered in the 1960s once satellite imagery allowed meteorologists to identify cloud structures that were too large to recognize from the ground. Often appearing over the ocean, these clouds can stretch over hundreds of kilometers, bringing drizzling rain. This…
“Timedrift II”
As a teenager, I climbed Mount Kilimanjaro. The final ascent began around midnight, and we climbed through the dark, through sunrise, and into the early morning. I remember pausing at one point, just as the sun was rising, and looking out at the clouds thousands of meters below. From that height, they looked like an…
Rotating Waves of Grains
Rotating drums are a popular way to explore granular dynamics. Here, researchers fill a cylinder (seen below) with heavy grains and a low-viscosity fluid, then rotate the mixture about a horizontal axis. This sets up a contest between centrifugal forces and gravitational forces on the grains. At the right rotation rates, the grains form annular…
Inside a Metal Vortex
What do you get when you combine liquid gallium, a blender, and a special probe lens? Some pretty wild slow-mo video of a liquid metal vortex, courtesy of the Slow Mo Guys. This video is almost as notable for its set-up as it is for the high-speed footage, given the lengths Gav and Dan go…
Neptune’s Seasonal Changes
Ice giant Neptune orbits our sun once every 165 years, meaning that each season on the planet lasts about 41 years here on Earth. Currently, the side of Neptune facing us is entering early summer, but a recent survey of atmospheric measurements show that Neptune’s stratosphere is experiencing some unexpected changes. Between 2003 and 2018,…