Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Lakes Upon Glaciers
Supraglacial lakes–ephemeral bodies of water that form atop glaciers–can form and empty in a matter of hours. The lakes typically empty either by overflowing their banks or by discharging through a moulin, a well-like crevasse in the ice. When this happens, the water from the lake drains into the bed beneath the glacier, acting like…
Schlieren in Flight
Schlieren photography is a common method of visualizing shock waves in wind tunnel experiments, but it’s much harder to pull off for aircraft in the sky. This video from NASA shows off some stunning work out of NASA Dryden capturing schlieren video of shock waves from a F-15B aircraft at Mach 1.38. You’ll notice that…
Droplet Collisions
When droplets collide, there are three basic outcomes: they bounce off one another; they coalesce into one big drop; or they coalesce and then separate. Which outcome we observe depends on the relative importance of the droplets’ inertia compared to their surface tension. This is expressed through the dimensionless Weber number, made up of density,…
Interview at Pointwise
There’s a new interview with me up at Pointwise’s Another Fine Mesh. In it I talk about FYFD, my advice to students, the future of CFD, women in engineering, the space program, and where to find great burgers. Be sure to check it out!
How Air Dancers Dance
Air dancers–those long fabric tubes with fans blowing into the bottom–are a popular way for shops to draw attention. They bend and flutter, shake and kink, all due to the interaction of airflow in and around them with the fabric. When the interior flow is smooth and laminar, the tube will stand upright, with very…
Dynamic Stall
In nature, birds and other flying animals often use unsteady flow effects to enhance the lift their wings generate. When a wing sits at a high angle of attack, it stalls; the flow separates from the upper surface, and its lift force is suddenly lost. If, on the other hand, that wing is in motion…
Fluids Round-up – 5 October 2013
This is the last week that my IndieGoGo project is open for donations. All money above and beyond what is needed for the conference will go toward FYFD-produced videos. Also, donors can get some awesome FYFD stickers. As a reminder, those looking for more fluids–in video, textbook, or other form–can always check out my resources page. And if you know…
Hydraulic Bumps
If you’ve ever noticed the circular jump in your kitchen sink when you turn on the faucet, you’re familiar with what a jet does when it plunges into a horizontal layer of liquid. If the liquid is deep enough, the jet will perturb the surface into a circular depression, as in Figure (a) above. As…
“Supermajor”
In Matt Kenyon’s “Supermajor,” oil appears to flow upward against gravity from a puddle into a can. This optical illusion is a stroboscopic effect similar to the one that makes car wheels seem to rotate backwards. The human eye and brain can be tricked into seeing the stream of oil as being suspended or even…
The Bathtub Vortex
If you’ve ever watched a swirling vortex disappear down the drain of your bathtub and wondered what was happening, you’ll appreciate these images. This dye visualization shows a one-celled bathtub vortex, created by rotating a cylindrical tank of water until all points have equal vorticity before opening a drain in the bottom of the tank. A recirculating…