Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Benard Cells
When a fluid in a gravitational field is heated from below, it can develop a Rayleigh-Benard instability which causes the formation of convection cells as in the video above. The hexagonal shape of the cells is due to the boundary conditions of the fluid. It’s possible to form other shapes like spirals. The same mechanism…
Human-Powered Ornithopter
A team at the University of Toronto has flown the world’s first human-powered ornithopter, an aircraft that flies by flapping its wings like a bird. The concept dates back all the way to Da Vinci in the 15th century. Part of why it’s taken centuries to realize the dream is that bird flight is much…
Breaking up in Crossflow
This video shows some instabilities that occur when a liquid jet impinges on a flowing cross stream. Note how the jet breaks down into droplets in a fashion similar to the Plateau-Rayleigh instability but the broken tip remains stable for some time thereafter. #
Supersonic
Moving supersonically–faster than the local speed of sound–can cause some awesome effects. Among these are vapor cones (a.k.a. Prandlt-Glauert singularities), shock waves, and, of course, the sonic boom.
Magnetohydrodynamics
Fluid dynamics play an important role in understanding phenomena like sunspots and solar prominences. The subfield of fluid dynamics concerned with the motion of electrically conducting fluids, like the plasma that makes up the sun’s corona, is magnetohydrodynamics.
How to Blow Bubble Rings
Next time you’re at the pool, join the dolphins, moss, and volcanoes in blowing vortex rings. Here’s how: first, squeeze your lips like you’re going to give someone a kiss. Second, increase the air pressure in your mouth. Then quickly open and close your lips so a small amount of air pops out. It can…
Mentos & Diet Coke in Microgravity
For a little Friday fun, consider this microgravity experiment conducted aboard the infamous Vomit Comet: what happens when you combine Diet Coke and Mentos in microgravity? For the record, I think this is the answer. (Via jshoer, who will be flying on the Vomit Comet in 2 weeks – but sadly not with a fluids…
Sailing Faster than the Wind
Is it possible to create a vehicle that uses the wind to move itself directly downwind faster than the wind does? Strangely enough, it is. The concept has been the subject of debate for years, but one team has confirmed the physics by building a vehicle that uses wind but can travel 2.8x faster than…
Non-Newtonian Fun
Non-Newtonian fluids are a favorite for displaying odd behaviors. High-speed video simply improves the experience. Remember, though, that non-Newtonian fluids don’t actually become solids when you hit them. They just react similarly to a solid because they exhibit a nonlinear response to deformation.
Microgravity Boiling
Boiling a liquid is a common enough phenomenon that we are all familiar with it. But, as with many aspects of fluid mechanics, removing gravity drastically changes the situation.