Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
The Mantis Shrimp’s Left Hook
The mantis shrimp is a tiny, clown-colored juggernaut of underwater physics. Some species have modified claws that serve as clubs for punching their prey, and the mantis shrimp swings that club fast – its acceleration is comparable to a bullet’s! Moving that quickly in water causes a drastic drop in local pressure, low enough to…
Vortex Reconnection
In slow motion, vortex rings can be truly stunning. This video shows two bubble rings underwater as they interact with one another. Upon approach, the two low-pressure vortex cores link up in what’s known as vortex reconnection. Note how the vortex rings split and reconnect in two places – not one. According to Helmholtz’s second…
“Pursuit”
Photographer Mike Olbinski has released yet another breathtaking timelapse film of weather over the Great Plains. This one has a little bit of everything: storms, tornadoes, incredible cloud formations, and even sunny days. Olbinski’s work is a reminder that there’s a constant beautiful drama playing out over our heads if we just take the time…
Leaping Droplets
Many fungi use coalescing water droplets to launch and spread their spores. The process is recreated in the laboratory in the animation above. Initially, there is a small spherical drop and a second, flattened drop stuck to the backside of the spore. In the animation, the large object on the right is actually both spore…
The Hydraulics Behind a Tuna’s Turns
Tuna are remarkably agile for their size. Many species reach lengths exceeding the height of a human adult, yet they can still make tight turns, especially when hunting. A recent study described one mechanism that aids the fish – a built-in hydraulic system for raising its second dorsal and anal fins. The tuna use fluid…
Watching Flow Inside Rock
Flow through porous substances has been a major interest in fluid dynamics for the last hundred years because rocks are porous. For most of that period, we’ve used Darcy’s law to calculate how a fluid flows through pores in a rock. (Incidentally, it can also be used for determining the perfect length of time for…
Flow Around a Cylinder
A cylinder standing upright in a flow creates a complicated system of vortices and recirculation. In the photo above, the flow is left to right. The cylinder itself is somewhat hard to see but is located in the center of the image; we see it from above. The colored streaks of dye show the flow…
Burning a Rocket Underwater
In a recent video, Warped Perception filmed a model rocket engine firing underwater. Firstly, it’s no surprise that the engine would still operate underwater (after its wax waterproofing). The solid propellant inside the engine is a mixture of fuel and oxidizer, so it has all the oxygen it needs. Fluid dynamically speaking, though, this high-speed footage…
The Elastic Leidenfrost Effect
Drop some hydrogel beads in a hot frying pan and they’ll bounce, hiss, and screech. Normally, if you drop a ball, it bounces to ever smaller heights until it comes to rest. In contrast, on a hot surface the hydrogel can bounce to a steady height for minutes at a time, raising a question: where…
Impressionist Gibraltar
Swirls of phytoplankton make this satellite image of Gibraltar look like an Impressionist painting. The photo is a composite of data from several instruments, with colors enhanced to highlight features of the phytoplankton blooms. The tiny plankton act as tracer particles that reveal some of the complex flow between the North Atlantic and the Mediterranean.…