Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Rotating or Not-Rotating?
Rotating a fluid often produces different dynamical behavior than for a non-rotating fluid. Here this concept is demonstrated by dropping creamer into a tank of water. Both experiments produce a turbulent plume, but the way the plume spreads and diffuses is much different in the case of the rotating tank, thanks to the Coriolis effect.…
Honey Coiling
The liquid rope coiling effect occurs in viscous fluids like oil, honey, shampoo, or even lava when they fall from a height. The exact behavior of the coil depends on factors like the fluid viscosity, the height from which the fluid falls, the mass flow rate, and the radius of the falling jet. Here Destin of the Smarter…
Space Didgeridoo
This week astronaut Don Pettit is playing with acoustic oscillators on the space station. He and Dan Burbank transform some of their vacuum cleaner tubes into didgeridoo-like instruments. By buzzing into the tube, Pettit is creating an acoustic standing wave, and, depending on the geometry at the far end, the wavelength of the standing wave…
Getting Ketchup to Flow
Most everyone is familiar with the difficulty of getting ketchup out of its bottle. Part of the trouble is that ketchup is a shear-thinning fluid, meaning that its viscosity decreases with an increasing rate of shear. Thus, a shear-thinning fluid flows better once it starts moving. This is why the ketchup moves much faster once…
Floral Still Life
Fluid motion is captured as a floral still life in these high-speed photos by Jack Long. The artist keeps mum about his set-up but notes that these are single capture events, not constructed composites. It looks as if the blossoms are created from the impact of a falling fluid with the upward jet that forms…
Hydrophobic Water Entry
Many factors can affect the size and shape of the splash when an object impacts water and wettability–the ability of a liquid to maintain contact with a solid–is one of them. Here a sphere coated in a hydrophobic (water-repellent) nano-layer impacts water, creating a large air, streaky air cavity and a substantial splash. Contrast this with…
Simulated Turbulence
This image, taken from a direct numerical simulation, shows turbulence in a stably stratified flow in which lighter fluid sits atop a denser fluid. In the image lighter colors represent denser fluid. Turbulence is created by the shear forces caused when the lighter fluid on top moves faster than the denser fluid on the bottom;…
Viscous Fingers
When less viscous fluids are injected into a more viscous medium, the low-viscosity fluid forms finger-like protrusions into the background fluid. This is known as the Saffman-Taylor instability. The video above shows this effect but in a more dynamic setting. Blue-dyed water and a clear solution of water and glycerol fifty times more viscous than…
Microgravity Cornstarch
We’ve seen the effects of vibration on shear-thickening non-Newtonian fluids here on Earth before in the form of “oobleck fingers” and “cornstarch monsters”, but, to my knowledge, this is the first such video looking at the behavior in space. The vibrations of the speaker cause shear forces on the cornstarch mixture, which causes the viscosity…