Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
A Drip’s Vortex
Drip food coloring into water and you can often see a torus-shaped vortex ring after the drop’s impact. That vortex rings form during droplet impact has been well known for over a century, but only recently have we begun to understand the process that leads to that vortex ring. Part of the challenge is that…
Ferrofluid Microlandscapes
Ferrofluids are an ever-fascinating topic. Consisting of ferromagnetic nanoparticles suspended in a carrier fluid, ferrofluids are known for their bizarre behaviors in the presence of a magnetic field, like their tendency to form pointed peaks reminiscent of Bart Simpson’s hair. In a new Concept Zero video, photographer Linden Gledhill creates fascinating micro-landscapes using ferrofluids suspended…
Self-Propelled Hovercraft
When placed on an extremely hot substrate, some drops levitate and can be propelled over specially textured surfaces. Inspired by this work, researchers are using similar principles to explore manipulation of levitating plates using surface texture. Their apparatus consists of a semi-porous, grooved surface that ejects air upward to levitate Plexiglas objects – think air…
Superhydrophobic Splashes
Superhydrophobic surfaces have a complicated microscale structure that changes how water interacts with them, like the hairs on a lotus leaf or the scales of a butterfly’s wing. The photo above shows snapshots at each millisecond as a water drop hits a superhydrophobic surface covered in rows of 18 micron-tall posts. The drop hits with…
Blue Man Group in Slow Mo
In their latest video, the Slow Mo Guys team up with the Blue Man Group for some high-speed hijinks, some of which make for great fluidsy visuals. Their first experiment involves dropping a bowling ball on gelatin. The gelatin goes through some massive deformation but comes out remarkably unscathed. Gelatin is what is known as…
Sky Glow
This short but spectacular timelapse video shows the Grand Canyon filled with fog. This phenomenon, known as a temperature inversion, occurs when a warm layer of air traps cold, moist air near the ground. As the inversion develops in the video, you can see wisps of clouds popping up in the canyon, seemingly out of…
The Perseus Cluster’s Bay
The Perseus cluster is a group of galaxies in the constellation Perseus. When viewed in x-ray, the cluster includes a concave feature known as the “bay”, shown in the white oval of the upper left image. A recent study uses x-ray and radio observations and computer simulations to argue that this feature is, in fact, a…
Spots of Turbulence
One of the enduring mysteries of fluid dynamics lies in the transition between smooth laminar flow and chaotic turbulent flow in the area near a wall. That region, known as the boundary layer, has a major impact on drag and other effects. The process begins with disturbances that are too tiny to see or measure,…
The Coalescence Cascade and Surfactants
Drops of a liquid can often join a pool gradually through a process known as the coalescence cascade (top left). In this process, a drop sits atop a pool, separated by a thin air layer. Once that air drains out, contact is made and part of the drop coalesces. Then a smaller daughter droplet rebounds…
Self-Digging Seeds
Some plants in the Pelargonium family produce seeds with long helical tails. These appendages, formally known as awns, are humidity-sensitive. On humid nights or after rainfall, the awn begins to straighten. With its end anchored on the ground, this unfurling spins the seed and helps it burrow into the soil. A study looking at the physics…