Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Rio 2016: Rugby
The sport of rugby returns to the Olympics in Rio this year. Rugby’s ball is somewhat similar in size and shape to an American football, but it is a little wider and more rounded. Aerodynamically, this means that the rugby ball has more drag, but it is also more stable in flight, allowing players to…
Rio 2016: Swimming
Strange as it seems, elite swimmers are faster when swimming underwater than they are at the surface. So much so, in fact, that they’re restricted to being underwater only 15 m after a dive or turn. To see just how stark a difference this makes, check out this crazy video. (I know, right?!) To understand…
Rio 2016: Cycling
Today marks the official start of the 2016 Summer Olympics in Rio. Here at FYFD we’ll be celebrating by taking a look at how fluid dynamics affects Olympic sports. You can check out our previous series on the London Olympics here. Since this weekend features the men’s and women’s cycling road races, we’ll get started…
Sharks Swimming Sideways
Like many sharks, the great hammerhead shark is negatively buoyant, meaning that, absent other forces, it would sink in water. To compensate, sharks generate lift with their pectoral (side) fins to offset their weight. Their dorsal (top) fin is used to generate the horizontal forces needed for control and turning. However, both captive and wild…
Spillway Waves
Earlier this summer, the spillway of the Banja Dam was opened for the first time, releasing a stream of excess water from the reservoir. As you can see above, waves quickly formed at the surface of the falling water. You’ve likely noticed this yourself in the run-off along the street after a storm. It turns…
Starting a Lighter
Lots of fluids are transparent, which makes it hard for us to appreciate their motion. One technique for making these invisible motions visible is schlieren photography, which makes differences in density visible. Here it’s combined with high-speed video to show what happens when you use a lighter (minus the spark!). When the fuel starts flowing,…
Hagfish Escape Mechanisms
The hagfish is an eel-like creature that has not changed much in the past 300 million years in part because the hagfish is very good at escaping would-be predators. When attacked, the hagfish excretes mucins that combine with seawater to form slime. This gel-like viscoelastic fluid forms quickly and has some handy properties. For example,…
The Evaporation of Ouzo
Ouzo is an aperitif made up of ethanol (alcohol), water, and anise oil. This three-part, or ternary, mixture undergoes an intriguing evaporation process thanks to the characteristics of its components. An ouzo drop’s evaporation can be divided into four phases, each shown above. Initially, the drop is well-mixed and transparent (upper left). Since ethanol is…
Crisscrossing Clouds
This natural-color satellite image shows crisscrossing cloud patterns off coastal Africa. These distinctive lines in the sky are gravity waves, and they form when air masses get displaced upward by terrain or other conditions. In this case, dry air cooled overnight on land before moving out over the ocean. That displaced warm, humid air above…
Crash Course Fluids
Crash Course Physics returns to the subject of fluids with their video on fluid dynamics. They stick with ideal fluids (i.e. incompressible, inviscid, laminar flows) for simplicity and cover some of the basics by discussing conservation of mass (also called continuity) and a simple form of Bernoulli’s equation. Despite keeping things basic, the video does…