Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
An Octopus’ Handshake
Cephalopods, especially octopuses, are fascinating creatures. At sea level, an octopus can generate an impressive pressure differential of 1 to 2 atmospheres with each of its suckers. That incredible grip is possible thanks to fluid dynamics. An octopus’s sucker consists of two main parts: the ring-shaped infundibulum on the outer surface and the inner, cup-shaped acetabulum.…
Vortex Impact
When a vortex ring impacts a solid wall (or a mirrored vortex ring), it expands and quickly breaks up. The animations above show something a little different: what happens when a vortex ring hits a water-air interface. As seen in the side view (top image), the vortex starts to expand, but its shear at the…
Breaking Soon
Australian photographer Warren Keelan captures spectacular photos of waves just before and during the moment they break. Fluid dynamics is defined by motion – specifically the motion of substances that do not hold a single form – but one thing I love about wave photography is how crisp and solid water appears when frozen in…
Venusian Waves
Despite its proximity, Venus remains largely mysterious, thanks to its cloudy atmosphere and incredible harsh conditions. A recent study using data from the Japanese satellite Akatsuki revealed an enormous bow-shaped wave in the Venusian atmosphere. The wave appeared at an altitude of about 65 km and stretched more than 10,000 km long, across both the northern…
Creating Clouds
What you see here is the formation of clouds and rain – but it’s not quite what you’re used to seeing outside. This is an experiment using a mixture of sulfur hexafluoride and helium to create clouds in a laboratory. Everything is contained in a cell between two transparent plates. Liquid sulfur hexafluoride takes up about…
Leidenfrost Atop a Fluid
Leidenfrost droplets typically hover on a thin layer of vapor above a surface that is much hotter than the boiling point of the liquid. Such drops move almost frictionlessly across these surfaces and can even propel themselves. The question of how hot is hot enough to produce the Leidenfrost effect is still being debated, but…
Leapfrogging Vortices
Two vortex rings travelling along the same line can repeatedly leapfrog one another. During my recent visit to the University of Chicago, PhD student Robert Morton of the Irvine Lab demonstrated this leapfrogging in the same apparatus they use to study knotted vortices. Leapfrogging works because of the mutual interaction of the flow fields of…
Happy Valentine’s Day
This heart-shaped atmospheric apparition is a lenticular cloud captured over the mountains of New Zealand. As you can see in the companion video, the cloud itself remains stationary over the mountain. This is a key feature of lenticular clouds, which form when air flowing over/around an obstacle drops below the dew point. This causes moisture…
Four Seasons
The team behind Beauty of Science decided to explore the four seasons in this video combining macro footage of crystal growth, chemical reactions, and fluid dynamics. It’s always a fun game with videos like this to try and guess exactly what makes the mesmerizing patterns we see. Are those blue streaming waves in Spring caused…
Self-Wrapping Drops
A liquid drop can fold itself up in a thin sheet. The animation above shows a drop of water with an ultra-thin (79nm) circular sheet of polystyrene atop it. As a needle removes water from the underside of the droplet, the shrinking droplet causes wrinkles and folds to form in the sheet. What’s going on…