Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Numerical Rayleigh-Taylor
If you’ve ever dripped food coloring or ink into a glass of water, you’ve probably created a cascade of tiny vortex rings similar to the images above. This is the Rayleigh-Taylor instability, in which the heavier ink/food coloring falls under gravity into the less dense water. What’s shown above is a special case–one that no…
“Monsoon II”
Every child learns about the water cycle in school, but an academic description of the process often lacks nature’s grandeur. In “Monsoon II” photographer Mike Olbinski captures the majesty of cloud formation and rainfall in a way that rekindles awe for the scale of the process. It begins with bright clouds popping up, the result…
Collecting Water in the Desert
Desert-dwelling plants like cactuses have to be efficient collectors of water. Many types of cactus are particularly good at gathering water from fog that condenses on their spines. Droplets that form near a spine’s tip move slowly but inexorably toward the base of the spine so that the cactus can absorb them. The secret to…
The Tightrope Dancers
Boiling is a process most of us don’t pay much attention to. But it can be remarkably entertaining and beautiful. This award-winning video shows boiling on and around a heated wire immersed in oil. Depending on the diameter of the wire and the power used to heat it, the researchers observe several different regimes of…
Hiding in the Sand
Flounders, stingrays, and other flat, bottom-dwelling fish often hide under sand for protection. These fish move by oscillating their fins or the edge of their bodies. They use a similar mechanism to bury themselves–quickly flapping to resuspend a cloud of particles, then hitting the ground so that the sand settles down to cover them. Researchers…
Icebergs and Caramel
What do icebergs and caramel have in common? Both have similar scalloped erosion patterns as they dissolve. When caramel dissolves in water, the denser caramel sinks in the buoyant water. An initially smooth surface will first form lines, then the flowing caramel and the uneven surface interact, forming chevrons, followed by larger scallops. A similar…
Drinking in Space
Earlier this year, the Capillary Beverage experiment launched to the International Space Station with new open-topped “Space Cups” for astronauts to test. Now those of us back on Earth are getting a glimpse of the cups in microgravity action. The geometry of the cups is wide on the back-end with a tightening v-shape near the…
The Fluidic Oscillator
A fluidic oscillator is a device with no moving parts that sprays a fluid from side to side. The animations above illustrate how they work. A nozzle funnels a fluid jet through a chamber with two feedback channels. When the jet sweeps close to one side of the chamber, part of the fluid is directed…
Fire Tornado
Fire tornadoes, despite their name, are more like dust devils than your typical tornado. In nature, they’ll often form in wildfires, but here the Slow Mo Guys simulate one for the high-speed cameras using a ring of box fans set up to provide rotational flow, or vorticity, around a kerosene fire. As the fire burns,…