Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
London 2012: Archery Physics
Archery is one of the oldest Olympic sports, but the physics involved are remarkably complex. Even looking only at the flight of the arrow, the problem is hardly simple. The heavy point of the arrow makes it front-heavy, and the fletches on the back of the arrow provide additional surface area on which air can act.…
London 2012: Swimming Pool Physics
The era of the LZR suit may be over in swimming, but technology is still making an impact when it comes to making swimmers faster. One thing you’ll often hear from commentators is how the London Aquatic Center boasts one of the world’s fastest pools. When swimmers compete, they have to contend with all the…
The Olympic Torch
[original media no longer available] Today marks the beginning of the 2012 Olympic Games in London. In the opening ceremony, the Olympic flame will complete its journey from Olympia to London, having been carried by some 8,000 torch bearers. Modern Olympic torches are expected to withstand wind, rain, snow, and human error to keep the…
Oil in Alcohol
In this video two droplets of oil fall through a bath of isopropyl alcohol. The oil is denser than alcohol, and the two fluids are miscible. The velocity and density gradients where the two fluids meet generate hydrodynamic instabilities that create the distinctive patterns seen in the falling drops. (Video credit: BYU Splash Lab)
Mussels
In this video, schlieren imaging is used to make visible the flow field around a mussel. Mussels are filter-feeders, drawing nearby water in to obtain their food and expelling the unneeded fluid once they’ve gathered the plankton they eat. Normally this process is invisible to the naked eye, but schlieren imaging reveals changes in density…
Sally Ride
Today FYFD takes a brief aside from fluid dynamics to mark the passing of Sally Ride, the first U.S. woman to travel to space. A physicist by training, Ride served as a mission specialist on STS-7 and STS-41G, shuttle missions that included deploying satellites as well as conducting scientific experiments. After her career with NASA,…
How Maple Seeds Fly
Maple tree seeds flutter and spin as they descend. The above video, which shows flow visualization of a freely falling seed, demonstrates that the so-called helicopter seed’s autorotation creates a vortex along the leading edge. Watch as the seed’s “wing” sweeps through and you will notice the vortex along the upper surface. This leading edge vortex…
Turing Patterns
Turing patterns form as a result of a particular kind of chemical reaction: a reaction-diffusion system. It consists of an activator chemical capable of making more of itself, and an inhibitor chemical which slows the production of the activator as well as a mechanism for diffusing the chemicals. Although Turing’s original work was theoretical in…
Vibrating Mercury
A drop of mercury on a vibrating teflon surface assumes various mode shapes as the amplitude and frequency of oscillation are changed. Note the geometry and symmetry of the mode shapes. Near the end of the movie, the mercury oscillates chaotically and all symmetry and pattern is broken. (Because mercury is toxic, do not try…
Liquid Pearls
Researchers create liquid pearls–a liquid droplet surrounded by a gel-like exterior–by dropping the fluid through a special bath. The initial droplet contains a mixture of the liquid core and an alginate solution. When the drop falls through a bath containing calcium ions, the alginate turns into a hydrogel shell around the liquid core. In order…