Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Bristling Scales Give Sharks Speed
The shortfin mako shark is one of the ocean’s fastest and most agile hunters, thanks in part to flexible scales along its body. As water flows around the shark’s body, the scales bristle to angles in excess of 60 degrees. This causes turbulence in the boundary layer along the shark’s body and prevents boundary layer…
Pterosaur Aerodynamics
The pterosaur was an enormous prehistoric reptile that flew with wings of living membrane stretched over a single long bone, unlike any of today’s flying creatures. New research using carbon fiber wing analogues and wind tunnel testing suggests that the pterosaur would have been a slow, soaring flyer well adapted to using thermals for lift.…
Superfluid Dripping
This high-speed video shows superfluid helium dripping and breaking up. Although superfluid has no viscosity, this does not prevent the Plateau-Rayleigh instability from breaking the helium into droplets once the mass of the liquid is too great for surface tension to contain.
Calcium Plasma on the Sun
This high-resolution photo of our sun shows the structure of calcium plasma on the surface of the sun. Plasmas are governed by the same physics as our familiar earthbound fluids but are also extremely sensitive to magnetic fields. Their branch of fluid dynamics is often referred to as magnetohydrodynamics (MHD), where the Navier-Stokes equations have…
Oil Chandeliers
What you see above is a composite of images of an oil droplet falling into alcohol from two different heights. The top row of images is from a height of 25 mm and the bottom from a height of 50 mm. The first droplet forms an expanding vortex ring which breaks down via the Rayleigh-Taylor…
Swimming in Corn Syrup
Highly viscous laminar flows exhibit kinematic reversibility, meaning: if you move the fluid one direction and then execute the same motion in the opposite direction, every fluid particle will return to its initial, undisturbed position. Above, you see a swimming device attempting to move through corn syrup by flapping. Because of this kinematic reversibility, it cannot…
Recreating Saturn’s Hexagon
In the 1970s, the Voyager spacecraft discovered a hexagon near Saturn’s north pole that defied explanation for years. However, researchers have since simulated the shape in a laboratory by placing a fast-spinning ring on the top surface of a slowly spinning column of fluid. Fluorescent dye is used to visualize the flow pattern. #
Tears of Wine
Tears of wine are caused by the Marangoni effect, in which a gradient in surface tension causes mass flow. The water in the wine has a higher surface tension than the alcohol in the wine, causing the wine to be drawn away from regions of higher alcohol concentration. #