Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Champagne Bubble Physics
Champagne is well-known for its effervescence, but its tiny bubbles do more than affect your sensation when sipping. Champagne bubbles form when carbon dioxide dissolved in the wine nucleates along imperfections in the glass. Buoyancy causes them to flow upwards, growing as they pull more carbon dioxide from the surrounding champagne. When the bubbles reach…
Healing Bubbles
Soap bubbles are ephemeral creations. The slightest prick will send them tearing apart in the blink of an eye. It may come as a surprise, therefore, that dropping a water droplet through a bubble will not break it. Instead, the bubble will heal itself using the Marangoni effect. In a soap bubble, the soap molecules…
Pyrocumulus Clouds
Pyrocumulus clouds tower tall above a wildfire in these photos taken last week from an Oregon National Guard F-15C. Most cumulus clouds form when the sun-warmed surface heats air, causing it to rise and carry moisture upward where it condenses to form clouds. In pyrocumulus clouds, the driving heat is supplied by a forest fire…
How Patterns Repel Water
Superhydrophobic surfaces repel water. Both naturally occurring and manmade materials with this property share a common feature: micro- or nanoscale structures on their surface. Lotus and lily leaves are coated with tiny hairs, and synthetic coatings or micro-manufactured surfaces like the one in the video above can be made in the lab. This nanoscale roughness…
Does Liquid in a Vacuum Boil or Freeze?
What happens to a liquid in a cold vacuum? Does it boil or freeze? These animations of liquid nitrogen (LN2) in a vacuum chamber demonstrate the answer: first one, then the other! The top image shows an overview of the process. At standard conditions, liquid nitrogen has a boiling point of 77 Kelvin, about 200…
Paint on Speakers
Paint seems to dance and leap when vibrated on a speaker. Propelled upward, the liquid stretches into thin sheets and thicker ligaments until surface tension can no longer hold the the fluid together and droplets erupt from the fountain. Often paints are shear-thinning, non-Newtonian fluids, meaning that their ability to resist deformation decreases as they are…
Why Do Joints Pop?
Joint popping is one of those things some people revel in and others detest. What you may not have realized, though, is that fluid dynamics are responsible for the sound. Joints contain a non-Newtonian liquid called synovial fluid to lubricate them. When you manipulate the joint to stretch it, pressure in the fluid drops and gases dissolved…
Reader Question: Winglets
Reader tvargo writes: First off… love your blog! I know very little about physics, but love reading about it. Could you potentially explain what the little upturned ends of wings do? looking on wikipedia is see this: “There are several types of wingtip devices, and although they function in different manners, the intended effect is…
The Real Shape of Raindrops
We often think of raindrops as spherical or tear-shaped, but, in reality, a falling droplet’s shape can be much more complicated. Large drops are likely to break up into smaller droplets before reaching the ground. This process is shown in the collage above. The initially spherical drops on the left are exposed to a continuous…
Rotational Effects
Rotation can cause non-intuitive effects in fluid dynamical systems. UCLA Spinlab’s newest video tackles the problem using four demonstrations. The first two deal with droplets released in air, first in a non-rotating environment and then in a rotating one. As one would expect, in a non-rotating environment, droplets fall through the tank in a straight…