Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Liquid Nitrogen and the Leidenfrost Effect
One of the tried and true cooking tips my mother gave me when I was younger was to test the temperature of my griddle before making pancakes by splashing a few drops of water on it. If it was hot enough that the water skittered across the surface before evaporating, then it was ready. Aside…
Drops Through Drops
The splashes from droplets impacting jets create truly mesmerizing liquid sculptures. Corrie White is one of the masters of this type of high-speed macro photography. Her work captures the instantaneous battles between viscosity, surface tension, and inertia. The fantastic structure seen here through the falling droplets is created by a series of drops timed so…
Reversing a Flow
The reversibility of laminar mixing often comes as a surprise to observers accustomed to the experience of being unable to separate two fluids after they’ve been combined. As you can see above, however, inserting dye into a highly viscous liquid and then mixing it by turning the inner of two concentric cylinders can be undone…
The Floating Water Bridge
The interaction of electric fields and fluids can lead to some unexpected results. Here we see the formation of a water bridge formed between two beakers of demineralized water across which a large voltage difference (~15kV) is applied. The bridge is stable for separation distances up to about 2 cm. In order to achieve this…
Mackerel vs. Eel: Who Swam It Better?
Which matters more, form or function? This simulation sets out to answer that question by comparing the swimming motion of eels and mackerels. Eels have longer, more rounded body shapes and swim in an undulatory fashion with their whole body, whereas mackerels have shorter bodies with a more elliptical cross-section and primarily move their tails…
Flying Squid
Ever seen a squid fly? Not many have, but the behavior may be more common than you think. Thanks to a set of photos from an amateur photographer, scientists have managed to estimate the velocity and acceleration of squid as they propel themselves out of the water by squirting a jet behind them. Researchers found…
Where Jupiter Got Its Swirls
When layers of a fluid are moving at different relative velocities, they shear against one another. This shear can trigger the Kelvin-Helmholtz instability, which develops as a waves along the interface. Here Hubble captures Kelvin-Helmholtz waves along the cloud bands of Jupiter, but such clouds are also not uncommon here on Earth. (Photo credit: J.…
The Gobbling Drop
A little polymer goes a long way when it comes to changing a fluid’s behavior. Normally, a falling jet of fluid will develop waviness and be driven by surface tension and the Plateau-Rayleigh instability to break up into a stream of droplets. We see this at our water faucets all the time. But when traces…
Solar Tornadoes
NASA’s Solar Dynamics Observatory captured this video of swirls of darker, cooler plasma caught between competing magnetic forces over the course of 30 hours. The plasma strands rotate like tornadoes caught on magnetic field lines. It sometimes feels incredible to observe such familiar-looking fluid behavior in such unfamiliar places, but it’s just a reminder that…
Making Mixed Emulsions
Ever tried to mix oil and vinegar? Anyone who has ever dealt with salad dressings knows the difficulty of evenly distributing immiscible fluids; the key is to shake them and create an emulsion, where droplets of one fluid are distributed throughout another. In this video, researchers create a double emulsion–oil in water in oil–without touching…