Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Ocean Waves in the Sky
These wave-like Kelvin-Helmholtz clouds can form due to shear between different layers of air in the atmosphere. When one region of air has a higher velocity than the other, their interface forms a shear layer, which can break down in this wavy pattern. In this case, the lower layer of air was moist enough to…
The Water Bridge
This short film offers an artistic look at the phenomenon of the water bridge. When subjected to a large voltage difference, such as the 30 kV used in the film, flow can be induced between water in two separated beakers. This creates a water bridge seemingly floating on air. There are two main forces opposing…
The Kaye Effect
The Kaye effect is an instability particular to a falling stream of non-Newtonian fluids with shear-thinning properties. When these fluids are deformed, their viscosity decreases; this, for example, is why ketchup flows out of a bottle more easily once it’s moving. Like most fluids, the falling shampoo creates a heap on the surface. The Kaye effect is…
Bouncing and Break-Up
In the collage above, successive frames showing the bouncing and break-up of liquid droplets impacting a solid inclined surface coated with a thin layer of high-viscosity fluid have been superposed. This allows one to see the trajectory and deformation of the original droplet as well as its daughter droplets. The impacts vary by Weber number,…
Saffman-Taylor Demo
In this video, a thin film of viscous glycerin sits between two glass plates. As the plates are forced apart, air gets entrained from either side, causing finger-like instabilities to form between the two fluids. This is a result of the Saffman-Taylor mechanism. The final dendritic pattern depends on the fluid viscosities, surface tension, and…
Ripples
Capillary waves–ripples–interfere with one another after the photographer throws objects into a narrow point in a small lake. The reflections of these waves off the lake’s boundaries and against one another creates a mosaic-like geometric effect on the liquid surface. (Photo credit: Jorgen Tharaldsen/National Geographic Photo Contest)
Flame Thrower Physics
This high-speed video–which we do not recommend recreating yourself–features burning gasoline flying through the air. In addition to the sheer entertainment value, there are some neat physics. In the first segment, when they kick a tray of gasoline, one can see lovely fiery vortices forming around the backside of the tray as it’s launched. This…
Lenticular Clouds
Lenticular clouds, such as the one shown above, are stationary lens-shaped clouds that form over a mountain or range of mountains. Moist air is deflected up over the mountain, and, if the temperature at higher altitudes is below that of the dew point, the water vapor in the air can condense, forming a cloud that…
Champagne Science
Today many a glass of champagne will be raised in honor of the end of one year and the beginning of a new. This French wine, known for its bubbly effervescence, is full of fascinating physics. During secondary fermentation of champagne, yeast in the wine consume sugars and excrete carbon dioxide gas, which dissolves in…
Bouncing in a Corral
About a year ago, we featured a video in which a fluid droplet bouncing on a vibrating pool demonstrated some aspects of the wave-particle duality fundamental to quantum mechanics. Work on this system continues and this new video focuses on studying some of the statistics of such a bouncing droplet–called a walker in the video–when…