Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Martian Viscous Flow
These images from the Mars Reconnaissance Orbiter show what are called viscous flow features. They are the Martian equivalent of glacial flow. Such features are typically found in Mars’ mid-latitudes. Ground-penetrating radar studies of Mars have shown that some of these features contain water ice covered in a protective layer of rock and dust, making…
Rotating Jet
This photo, one of the winners of the Engineering and Physical Sciences Research Council’s (EPSRC) annual photography contest, shows a rotating viscoelastic jet. Rotating liquid jets are common to many manufacturing processes, and their sometimes-wild appearance comes from a balance of gravitational forces and centrifugal force against surface tension. But because this fluid contains a small…
Filter-Feeding Mantas
Large filter-feeders like the manta ray face the interesting challenge of obtaining enough small particulates like plankton to sustain an animal the size of a car. They do this through what is known as ram filter-feeding, essentially swimming open-mouthed through food-laden waters, filtering out the food, and releasing the water through their gills. Their internal…
Wrinkling Fluids
What you see here is a viscous drop falling into a less viscous fluid. Shear forces between the drop and the surrounding fluid cause the drop to quickly deform into a shape like an upside-down mushroom as it descends. The cap forms a vortex ring that curls the viscous fluid back on itself. As it…
Singing Sand Dunes
Reports of singing sand dunes date at least as far back as 800 C.E. Strange as it sounds, about forty sites around the world have been associated with this phenomenon, in which avalanches of sand grains on the outer surface of the dune cause a deep, booming hum for up to several minutes. As you…
Review: “Life in Moving Fluids”
If you liked the prairie dog post earlier this week and you’re interested in more examples of biological fluid dynamics, you may enjoy Steven Vogel’s “Life in Moving Fluids”. I’m often asked for suggestions of readable textbooks for those who want an introduction to fluid dynamics, and this book is a great option. It addresses…
Dyeing the River
Every year Chicago dyes part of its river green to celebrate St. Patrick’s Day. This timelapse video gives a great view of the 2016 dyeing. If you watch closely, you’ll see that what’s being put in the river isn’t originally green. It’s actually an orange powder being distributed through flour sifters by the men on…
Dancing Droplets
The seemingly-alive dancing droplets are back in a new video from Veritasium. These droplets of food coloring attract, merge, and chase one another due to evaporation and surface tension interactions between their two components: water and propylene glycol. Because the droplets are constantly evaporating, they are surrounded by a cloud of vapor that helps determine…
Prairie Dog Physics
One challenge facing burrowing mammals is ensuring sufficient oxygen within their den. Prairie dogs achieve this with a clever use of Bernoulli’s principle. They build multiple entrances to their tunnels. One of them, labeled as Entrance A above, is built with a raised mound of dirt, while the other, Entrance B, is not. The raised…
Pyroclastic Flow
Major volcanic eruptions can be accompanied by pyroclastic flows, a mixture of rock and hot gases capable of burying entire cities, as happened in Pompeii when Mt. Vesuvius erupted in 79 C.E. For even larger eruptions, such as the one at Peach Spring Caldera some 18.8 million years ago, the pyroclastic flow can be powerful…