Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
How Fluid Dynamics Saved the Space Shuttle
New FYFD video! In which Dianna Cowern (Physics Girl) joins me to explore boundary layer transition and how a couple of small bits of roughness could be a huge problem for the Space Shuttle during re-entry. A lot of people have asked me what I did for my PhD research, and the truth is, I’ve…
Climbing Up the Walls
You may have noticed when baking that fluids don’t always behave as expected when you agitate them. If you put a spinning rod into a fluid, we’d expect the rod to fling fluid away, creating a little vortex that stirs everything around. And for a typical (Newtonian) fluid, this is what we see. The fluid’s…
Bursting Into Droplets
Our atmosphere is full of aerosols – extremely tiny particles and droplets of salt, dust, pollutants, and other substances. Wind’s effects alone cannot account for the sizes and quantities of aerosols we measure. Another potential source is the bursting of bubbles; more specifically, the bubbles that form at the oceans’ surface. Frothy, crashing waves often…
Whiskey Stains
Photographer Ernie Button discovered that whiskey left behind intriguing patterns after it evaporated. Unlike coffee rings, the whiskey leaves behind a more uniform residue. Curious, he contacted researchers at Princeton, who were eventually able to explain why whiskey and coffee dry so differently. They observed three major effects in drying whiskey mixtures. Firstly, the alcohol…
Vortex Ring Roll-Up
Vortex rings are endlessly fascinating, and they appear throughout nature from dolphins to volcanoes and from splashes to falling drops. One way to form them is to inject a jet into a stationary fluid. Viscosity between the fast-moving jet and the quiescent surrounding fluid slows down fluid at the jet’s edge. That slower fluid slips…
“Bubble Circus”
The “Bubble Circus” is a delightful outreach device equipped for all manner of physics demos, as seen in the video above. Many of its exercises explore surface tension, a force observed at the interface of a fluid. Surface tension is what provides bubbles with their surface-minimizing spherical shape. That same property determines the minimal distance…
Flying with Large Ears
Evolution often requires compromise between competing effects. Large-eared bats, for example, rely on the size of their ears to aid their echolocation, but such large ears can hurt them aerodynamically, thus limiting their flight. Results from a recent experiment, however, suggest that large ears are not a total loss aerodynamically speaking. Researchers used particle image…
Foggy Flows
The transparency of air makes it easy to overlook its fluid nature. In this National Geographic Travel Photographer of the Year entry, photographer Thierry Bornier captures the early morning view from China’s Yellow Mountain. Foggy clouds flow around and over nearby mountain peaks, like water flowing over rocks in a stream. To see other, similar…
Bioluminescent Plankton
The blue-outlined dolphins you see above get their glow from microorganisms called dinoflagellates. They are a type of bioluminescent plankton, shown in the lower image, that can be found in oceans around the world. Their glow comes from combining two chemicals: luciferase and luciferin. The dinoflagellates suspended in the ocean do this when they are…
The Blue Whirl
Researchers studying the use of fire whirls to burn off oil spills have discovered a new type of fire whirl – the blue whirl. Their results are currently reported in a pre-print paper on arXiv and await peer-review. In their experiment, the scientists ignited a puddle of fuel floating atop water. Compared to a typical…