Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
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…
Dust Devils
Dust devils, like fire tornadoes and waterspouts, form from warm, rising air. As the sun heats the ground to temperatures hotter than the surrounding atmosphere, hot air will begin to rise. When it rises, that air leaves behind a region of lower pressure that draws in nearby air. Any vorticity in that air gets intensified…
Martian Ripples
Earth and Mars both feature fields of giant sand dunes. The huge dunes are shaped by the wind and miniature avalanches of sand, and their surface is marked by small ripples less than 30 centimeters apart. These little ripples are formed when sand carried by the wind impacts the dunes. But Martian dunes have a second,…
These Invertibrates May Help Robots Swim
New FYFD video! Learn all about salps, vortex rings, and underwater robots. Thanasi Athanassiadis takes me inside his lab and his newly published research into how proximity affects the thrust two vortex rings can produce. There are a ton of little things I love about how this video came out, especially the chalkboard animations. Check…
Quarry Smashing
Despite appearances, this is not a crashing ocean wave. In fact, it’s a planned explosion at a quarry, and that wave is more than 360,000 tons of rock and 68 tons of explosive pouring down. The scale of this is hard to imagine, and the physics of a ocean breaker and a massive wave of…
The Knuckleball
For more than a century, athletes have used the zigzagging path of a knuckleball to confound their opponents. Knuckleballing is best known in baseball but appears also in volleyball, soccer, and cricket. It occurs when the ball has little to no spin. The source of the knuckleball’s confusing trajectory, according to a new study, is…
Granular Plugs
Imagine filling a narrow tube with a mixture of water and tiny glass beads. Then take a syringe and very slowly start drawing out the water. As the water gets sucked out of the tube, air will be pulled into the opposite end. The meniscus where the air and water meet sweeps up the glass…