Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Are Cats a Fluid?
Are cats a fluid? It’s a question that has inspired many a meme. There are a few common definitions as to what makes a fluid. One is that a fluid changes its shape to that of its container. Another more technical definition is that a fluid deforms continuously under shear forces. But the real picture…
Starfish Vortices
Starfish larvae, like other microorganisms, use tiny hair-like cilia to move the fluid around them. By beating these cilia in opposite directions on different parts of their bodies, the larvae create vortices, as seen in the flow visualization above. The starfish larvae don’t use these vortices for swimming – to swim, you’d want to push…
Saturnian Clouds
It may look like an oil slick, but the photo above actually shows the clouds of Saturn. The false-color composite image reveals the gas giant in infrared, at wavelengths longer than those visible to the human eye. NASA uses this infrared photography to identify different chemical compositions in Saturn’s atmosphere based on how they reflect…
Coarsening in a Soap Film
Flow in a soap film is driven by gravity’s efforts to thin the film and surface tension’s attempts to stabilize variations in thickness. Because evaporation guarantees that the soap film will eventually dry out, gravity typically wins the battle and causes a soap film to rupture. This video takes a close look at what happens…
Oil in Alcohol
A drop of oil impacts and falls through a pool of isopropyl alcohol. Momentum, viscosity, and diffusion combine to deform the drop into a shape that is initially like an upside-down wine glass (top image). Because the oil is both denser than the alcohol and soluble in it, the drop sinks and dissolves as it…
APS DFD 2016
It’s the time of year again for the American Physical Society Division of Fluid Dynamics meeting! Tomorrow I’ll fly to Portland, OR for three days of non-stop fluid dynamics. This year I’ll be giving two talks: – Sunday, November 20th, 3:23pm, Room B117: F*** Yeah Fluid Dynamics: Inisde the science communication process – Monday, November…
The Blue Whirl
We wrote earlier this year about the discovery of a new type of fire whirl – the blue whirl – but now the authors have published video of the blue whirl in action! The blue whirl was discovered while investigating the use of fire whirls to more efficiently burn off oil spilled atop water. A tightly…
A Particle-Filled Splash
A drop of water that impacts a flat post will form a liquid sheet that eventually breaks apart into droplets when surface tension can no longer hold the water together against the power of momentum flinging the water outward. But what happens if that initial drop of water is filled with particles? Initially, the particle-laden…
Surfing on Vapor
Place a drop of liquid on a surface much, much hotter than the liquid’s boiling point, and the portion of the drop that impacts will vaporize immediately. This leaves the droplet hovering on a thin layer of vapor. With a fluid like water, the vapor state is a much more efficient insulator than the liquid…
Bouncing Droplets
Droplets bouncing on a pool form a beautiful and fascinating system, as recently featured by Physics Girl, Veritasium, and Smarter Every Day. The Lutetium Project – a consortium of French physics, graphic design, and music students – have their own take on the subject with beautiful short videos constructed from experimental research footage. With simple…