A bioluminescent phytoplankton bloom is causing a stir among California beachgoers. During the daytime, aggregations of Lingulodinium polyedra appear reddish-brown in color (think the classic ‘red tide’). But at night Keep reading
Tag: shear
Sliding Foams
What happens when a foam interacts with a sliding surface? That’s the question at the heart of this study, which finds three major regimes of foam-surface interaction. On smooth surfaces Keep reading
Wave Clouds in the Front Range
Last Sunday night metro Denver was treated to a rare sight: clouds resembling breaking waves formed near sunset. These are Kelvin-Helmholtz clouds, and the comparison to ocean waves is apt, Keep reading
Shearing Grains
Granular materials, like beads and sand, demonstrate both solid and fluid-like behaviors, which makes them difficult to study. Traditionally, one method for studying how fluids respond to deformation places the Keep reading
Waves on a Supercell
This Colorado supercell thunderstorm features an unusual twist. Notice the sawtooth-like protrusions along the outer cloud wall. These are Kelvin-Helmholtz waves, like these fair-weather clouds we’ve seen before, but instead of occurring vertically, they Keep reading
Waves in the Sky
Even when the sky is mostly blue, there’s a lot going on at different altitudes. The winds do not move in a consistent direction or at the same speed, something Keep reading
Asymmetric Wakes
When a ship moves through water, it leaves a distinctive V-shaped wake behind it. In the nineteenth century, Lord Kelvin made some of the earliest theoretical studies of this phenomenon, calculating that Keep reading
Storing Memory in Bubbles
Soft systems like this bubble raft can retain memory of how they reached their current configuration. Because the bubbles are different sizes, they cannot pack into a crystalline structure, and Keep reading
Floccing Particles
Adding particles to a viscous fluid can create unexpected complications, thanks to the interplay of fluid and solid interactions. Here we see a dilute mixture of dark spherical particles suspended Keep reading
Communication Between Microswimmers
The elongated cells of Spirostomum ambiguum swim using hair-like cilia, but when threatened, the cells contract violently, sending out long-range hydrodynamic waves, like those visualized above. Along with these waves, the Keep reading