Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Collective Motion: Waving Bees
Giant honeybees live in huge open nests. To protect themselves, they’ve developed a mesmerizing wave-like defense known as shimmering. When shimmering, the bees in a hive, beginning from a distinct spot, will flip over to expose their abdomens. Taken together, this creates large-scale patterns like those seen above. Scientists have connected the behavior to the…
Collective Motion: Crowds
It’s sometimes taken for granted that, in groups, people can behave a lot like a fluid or a granular material. This allows scientists to adapt models developed for those materials to understand how crowds move. But in doing so, it’s always important to test just how far the comparison holds; in other words, just how…
Collective Motion: Worms
Although most animals are more solid than fluid, what happens when you put many of them together can be strikingly fluidic. Above you see the black aquatic worm, Lumbriculus variegatus, which must keep moist to stay alive. An individual worm will die within an hour of being removed from the water, but, in a group,…
Collective Motion: Intro
Herds, flocks, schools, and even crowds can behave in fluid-like ways. On Science Friday, Stanford professor Nicholas Ouellette explains some of the physics behind these similarities. Fluids are, after all, made up of a many, many individual particles – typically molecules – just the way a crowd of people or a school of fish contains…
Avoiding Ice
Keeping ice from forming on a surface is a major engineering challenge. Typically, there’s no controlling certain factors – like the size and impact speed of droplets – so engineers try to tame ice by changing the surface. This can be through chemicals – as with deicing fluids used on aircraft – or by tuning…
Simulating Solar Flares
Few topics in fluid dynamics are more mathematically complicated than magnetohydrodynamics – the marriage between electromagnetism and fluids. That mathematical complexity, along with the vast range of scales necessary to describe physical systems like our sun, means that, until now, researchers had to simplify their assumptions when simulating solar physics. But now, for the first…
Liquid Antispiral
Spiral formations are common in nature, from galaxies to chemical reactions. But most examples in nature rotate such that their arms trail the direction of rotation. Viewed side-on, this makes the arms appear to spiral outward from the the center. The opposite – an antispiral, where the arms appear to be drawn in toward the center…
Worthington and His Jets
If you’ve been around fluid mechanics for very long, you’ve probably noticed that we like to name things after people. (Mostly dead, white guys, but that’s another subject.) Whenever someone describes or explains a new phenomenon, it tends to get their name attached to it. Some of the common names in fluid dynamics – Reynolds,…
The Polar Vortex
Every year or two, the Northern Hemisphere gets treated to a bout of intensely cold temperatures thanks to the polar vortex. What you may not realize, though, is that it’s not the polar vortex that causes this cold weather – it’s the vortex breaking down. As Simon Clark explains in this video, the polar vortices…
Dripping Down the Rivulet
If you’ve ever watched water running down the side of the street, you’ve probably noticed that it doesn’t flow smoothly. Instead, you’ll see waves, rivulets, and disturbances that form. That’s because the simple action of flowing down an incline is unstable. Water and other viscous liquids can’t flow downhill smoothly. Any disturbances – an uneven…