Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Supercavitating Penguins
[original media no longer available] Penguins, already fluid dynamicists by nature, have developed clever methods of increasing their speed to escape from the leopard seals that prey on them. In the clip above, notice from 1:55 onward as the penguins swim for the surface and leap onto the ice – they leave a trail of…
Reader Question: Fire as a Fluid?
Reader David L asks: I understand that fire is a form of energy rather than a fluid in the physical/tangible sense. However, is it possible for fire to exhibit fluid-like behaviours to a certain extent. In other words, could the dynamic properties of fire be described with pseudo-variables analogical to variables that describe a physical…
Bursting Bubbles
Sometimes bursting one bubble just leads to more bubbles. This high-speed video shows how popping a bubble sitting on a fluid surface can lead to a ring of daughter bubbles. When the surface of the bubble is ruptured, filaments of the liquid that made up the surface are drawn back toward the pool by surface…
F-18 Flow Viz
Water tunnels are useful tools for determining aerodynamic characteristics of aircraft, such as this F-18 model placed in the NASA Dryden Flow Visualization Facility. By matching the Reynolds number of the model in the water tunnel to that of the full-scale aircraft in air, engineers can observe flow around the aircraft inside the laboratory. This…
“Ferroux”
In this video, artist Afiq Omar mixes ferrofluid with soap, alcohol, milk, and other liquids to create a surrealistic fluidic dance. In addition to using different fluid mixtures, I suspect he accomplishes many effects using several different permanent magnets and electromagnets to vary the magnetic fields around the ferrofluid mixtures. (Video credit: Afiq Omar; via…
Flapping to Fly Efficiently
High-speed video shows that bats achieve some of their efficiency in flight by pulling their wings inward on the upstroke, as seen above. While this does affect drag forces on the wing slightly, the primary energy savings comes from the inertial ease of lifting the folded wing. Much the way it is easier to lift…
Fixing Potholes with Oobleck
Shear-thickening non-Newtonian fluids like oobleck become more viscous as force is applied to them. This behavior causes them to form finger-like structures when vibrated, makes it good liquid armor, and even enables people to run across a pool of it without sinking. Now undergraduates at Case Western Reserve University have found a new use for such fluids: pothole…
Vibrating Oil
This high-speed video shows the behavior of oil on a vibrating surface. As the amplitude of the vibration is altered various behaviors can be observed. Initially small waves appear on the surface of the oil, then the surface erupts into a mass of jets and ejected droplets, reminiscent of a vibrated interfaces within a prism or vibration-induced…
Jumping Water Droplets
Superhydrophobic surfaces resist wetting from water, but it turns out they can also trigger interesting behaviors in the tiny droplets condensing on the surface. High-speed video reveals that when two condensate droplets coalesce, the energy released by surface tension causes the new droplet to jump off the surface. The phenomenon is the same as one observed…
Frozen Fluid Illusion
This video creates the illusion of a jet of water frozen in mid-air. The effect is achieved by vibrating the water at the frequency of the speaker, then filming at a frame rate identical to the vibrational frequency. Thus the water pulses at the exact rate that the camera captures images, making the water appear…