Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Swept Along
When a car drives over a leaf-strewn autumn road, it pulls leaves up with its passage. This tendency to drag fluid along when an object passes is called entrainment, and it may be a key to transporting loads like medicine in microfluidic applications. As shown above, a self-propelled microswimmer — in this case, an oil…
“Halo”
Fluids create mesmerizing practical effects in this new experimental film from the Julia Set Lab. I love how the visuals mess with your sense of scale. Some of the sequences look like they could be a solar firestorm or disintegrating sea ice, though in reality the camera’s field of view is probably smaller than your…
The Assassin’s Teapot
The assassin’s teapot is a cleverly designed container that can pour from different reservoirs depending on how it’s held. Steve Mould digs into the physics in this video, and he builds a transparent cutaway version of the pot to show exactly how it works. This design uses two separate reservoirs, each with two holes —…
Elastic Turbulence
Decades ago, engineers pumping polymer-filled drilling liquids into porous rock noticed sudden and dramatic increases in the viscosity of the liquid. Within the tiny pores of the rock, conventional (i.e., inertial) turbulent flow should be impossible — the Reynolds number is simply too low. Now a new experiment points to the source of the high…
The Yarning Droplet
Marangoni bursting takes place in alcohol-water droplets; as the alcohol evaporates, surface tension changes across the liquid surface, generating a flow that tears the original drop into smaller droplets. Here researchers add a twist to the experiment using PMMA, an additive that dissolves well in alcohol but poorly in water. As the alcohol evaporates, the…
Viscosity and Quantum Mechanics
Viscosity describes a fluid’s resistance to changing its shape. Like surface tension, it’s a fundamental property of a fluid that comes from the interactions between molecules. But viscosity is a slippery beast, and especially so for liquids. There is no generic way to calculate a liquid’s thermodynamic properties from quantum dynamical first principles. But that…
Moody Waves
Lines of waves emerge from thick morning fog in this series by photographer Raf Maes. The eerie, slightly surreal images were captured in Venice, near Los Angeles. So often ocean photography features huge, turbulent breaking waves. I find it really neat to see these long, unbroken wave crests appearing from the mist. (Image credits: R.…
The Return of the Ice Disk
Maine’s giant, spinning ice disk is taking shape again. In 2019, it reached about 91 meters across, rotating slowly in the Presumpscot River. How exactly these features form is still a matter of debate, but scientists have worked out a few relevant mechanisms. The spinning of the disk seems to depend on a vortex that…
Laser-Induced Jet Break-Up
A falling stream of water will naturally break up into droplets via the Plateau-Rayleigh instability. Those droplets are random, unless something like vibration of the nozzle sets their size. In this study, though, researchers found that shining a laser beam on the stream can trigger an orderly break-up with droplets that are consistent in size…
Volcanic Shocks
A violent underwater eruption at the Hunga Tonga-Hunga Ha’apai caldera on January 15th sent literal shock waves around the world. This animation, based on satellite images from Japan’s Himawari 8, shows the fast-moving shock waves and the growing ash plume coming from the uninhabited island. Although most recent eruptions from this volcano have been small,…