Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Colorful Spirals
Artist Fabian Oefner captures these colorful portraits of fluid instability by dripping acrylic paints onto a metal rod, which is connected to a drill. When the drill is switched on, paint is flung away from the rod, creating these snapshots of centripetal force and surface tension. Note how droplets gather at the ends of the…
Mixing the Southern Ocean
Motion in the ocean is driven by many factors, including temperature, salinity, geography, and atmospheric interactions. While global currents dictate much of the large-scale motion, it’s sometimes the smaller scales that impact the climate. This visualization shows numerically simulated data from the Southern Ocean over the course of a year. The eddies that swirl off…
Lift on a Paper Plane
In this still image from a student experiment, smoke visualization shows the formation of a vortex over the wing of a paper airplane during a wind tunnel test. This wing vortex is mirrored on the opposite wing, though there is no smoke to show it. At high angle of attack, the delta-wing shape of the…
Mixing While Laminar
Although turbulent flows are known for their mixing efficiency, in manufacturing there can often be a need to mix laminar fluid streams without the increased shear stress of a turbulent flow. This can be particularly important for polymeric liquids, where too much shear stress could damage the polymer chains. One possibility is using a static…
The Boundary Layer Visualized
Any time there is relative motion between a solid and a fluid, a small region near the surface will see a large change in velocity. This region, shown with smoke in the image above, is called the boundary layer. Here air flows from right to left over a spinning spheroid. At first, the boundary layer…
Under the Waves
When I was a kid, I liked to dive underwater in the pool and sit at the bottom, looking up at the peculiar dancing sky the water made overhead. Photographer Mark Tipple takes it further, capturing images of the ocean from below the surface as waves roll in. His photos show swimmers and surfers diving…
Frozen Methane Bubbles
As the Arctic warms, methane that was previously trapped by permafrost rises from the muddy bottom of lakes to escape into the atmosphere. Here the first clear ice of the fall has trapped the rising methane bubbles, allowing scientists an opportunity to estimate the amount of methane being released. When spring arrives and the lakes…
“Frozen” Water Stream
We saw previously how vibrating a falling stream of water and filming it with a matching camera frame rate appears to “freeze” the falling liquid. This video shows the same illusion, now with a 24 Hz sine wave, which the falling water mimics. Vibrating the speaker that drives the water stream slightly slower or slightly…
Inside a Blender
The fluid dynamics of a commercial-quality blender amount to a lot more than just stirring. Here high-speed video shows how the blender’s moving blades create a suction effect that pulls contents down through the middle of the blender, then flings them outward. This motion creates large shear stresses, which help break up the food, as…
Tuning Fork Fluids
This high-speed video shows a liquid crystal fluid vibrating on a tuning fork. As the surface moves, tiny jets shoot upward, sometimes with sufficient energy that the fluid column is stretched beyond surface tension’s ability to keep it intact, resulting in droplet ejection. The jets and surface waves create a mesmerizing pattern of fluid motion.…