Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Antibubbles
Antibubbles–a liquid droplet surrounded by a thin film of gas and immersed in more liquid–are fragile things. This video explores how antibubbles behave when placed in proximity to a tornado-like whirl. When placed near the eye, where fluid motion is primarily vertical, the antibubble is stretched vertically. When placed in the rotating eyewall, the antibubble…
Fractal Fluids
These images from a numerical simulation of a mixing layer between fluids of different density show the development and breakdown to Kelvin-Helmholtz waves. The black fluid is 3 times denser than the white fluid, and, as the two layers shear past one another, billow-like waves form (Fig 1(a)). Inside those billows, secondary and even tertiary…
How Mosquitoes Fly in the Rain
One might think that rainfall would keep the mosquitoes away, but it turns out that rain strikes don’t bother these little pests much. Because the insect is so small and light compared to a falling raindrop, the water bounces off instead of splashing. This results in a relatively small transfer of momentum, although the mosquito…
Dancing Sands
Here a collection of dry grains are vertically vibrated, creating a series of standing waves on the surface of the sand. The shapes of these Faraday waves are dependent upon the frequency of the vibration. Despite the solid nature of sand particles, this behavior is much the same as the behavior of a vibrated fluid.
Splash Rebound
A ball dropped onto a puddle loses some of its rebound momentum to fluid motion. On impact, a splash curtain and radial jet form as the fluid is displaced by the ball. As the ball rebounds, the splash curtain is drawn inward into a column of fluid drawn up by the ball, reminiscent of the way cats…
Dolphin Bubble Rings
Dolphins create vortex rings to play with by exhaling through their blowholes. The sharp impulse of air, combined with the round shape, creates a vortex ring of bubbles. Humans can do this underwater, too, but dolphins aren’t content to lie at the bottom of the pool. Because smaller vortex rings are more coherent and last…
Rapid Freezing
Thermodynamics can play strange games with liquids. Here a bottle of chilled soda water is used to demonstrate a method of rapid freezing. Because the water is at a higher pressure than atmospheric, its temperature can be lower than the normal freezing point in a standard atmosphere. This is why the soda water remains a…
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…