Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Making Droplets
If you’ve ever wondered how fluid dynamicists create those tiny perpetually bouncing droplets they study, wonder no further. A typical method, shown here, is to use a simple toothpick. First, you take a shallow container of silicone oil and vibrate it vertically. Then you dip the tip of the toothpick into the oil and pull…
The Law of Urination
Tonight is the 26th Ig Nobel Prize ceremony. As I’ve covered previously, the subject of fluid dynamics has been quite successful at winning these awards designed to “make people LAUGH, then THINK,” and last year’s ceremony was no exception. Georgia Tech researchers won the Physics Prize last year for explaining why mammals of very different sizes…
Jovian Poles
We’re used to viewing Jupiter from its equator, where bands of light and dark clouds dominate the picture. From its poles, Jupiter looks very different, as these recent images from Juno show. Jupiter’s north pole is shown on the left and its south pole on the right. Both are awash in vortices. There’s another great…
Soap Film Turbulence
The brilliant colors of a soap film reveal the fluid’s thickness, thanks to a process known as thin film interference. The twisting flow of the film depends on many influences: gravity pulls down on the liquid and tends to make it drain away; evaporation steals fluid from the film; local air currents can push or…
Inside a Humidifier
After this, you may never look at a humidifier the same way again. Ultrasonic humidifiers generate tiny droplets using piezoelectric transducers. When the humidifier is on, the ultrasonic vibrations of the piezoelectric transducer create a pressure wave that forces the water above into a hill with a string of liquid droplets extending upward. For a…
Shark Tooth Instability
Imagine that you partially fill a horizontal cylinder with a viscous fluid, like corn syrup or honey. If that cylinder is still, the fluid will simply pool along the bottom. On the opposite extreme, if you spin it very fast, that cylinder will become coated in an even layer of fluid that rotates along with…
Fog Over Marin
Fog rolls over the hills of Marin County in this long-exposure photograph by Lorenzo Montezemolo. One of the most beautiful aspects of fluid dynamics is the way the same patterns and forms show up across situations. The slow flow of fog over hills in moonlight can echo the blurring speed of rivers pouring over a…
Shear Across the Water
This photo series shows the development of a Kelvin-Helmholtz instability. It’s formed when two layers of fluid move past one another at different speeds. In this case, the two fluids meet off the back of a flat plate (seen at the left of the top image) when fast-moving flow from the top of the plate…
Droplet Bounce
Water droplets don’t always immediately disappear into a pool they’re dropped onto. If the droplet is small and doesn’t have much momentum, it will join the pool gradually through a process known as the coalescence cascade, seen here in high speed video. The droplet bounces off the surface, then settles. A thin layer of air…
Reader Question: Rudders
Reader le-mec writes: My question involves “fenestrated rudders”, a Chinese invention that involved cutting diamond-shaped holes in the rudders of ancient Chinese sailing ships (known as Junks). According to several articles (on the internet, ha ha), it reduces the amount of effort required to steer the ship at higher speeds with “no loss of function”.…