Swarm of Surfers

Self-propelled objects can form fascinating patterns. Here, researchers investigate how small plastic "surfers" move on a vibrating fluid.  (Image and research credit: I. Ho et al.; via APS Physics) Read the full article

"The Reef"

Artist Alberto Seveso returns to his colorful ink plumes, but this time with a twist. Here, Seveso took ink injected in water and digitally altered it, adding texture and shaping the ink to mimic the shapes of coral reefs.  (Image credit: A. Seveso; via Colossal) Read the full article

Droplet Medusa

Vibration is one method for breaking a drop into smaller droplets, a process known as atomization. Here, researchers simulate this break-up process for a drop in microgravity. (Image and research credit: D. Panda et al.) Read the full article

Controlling Finger Formation

When gas is injected into thin, liquid-filled gaps, the liquid-gas interface can destabilize, forming distinctive finger-like shapes. In laboratories, this mechanism is typically investigated in the gap between two transparent plates, a setup known as a Hele-Shaw cell.  (Image credit: C. Cuttle et al.; research credit: C. Cuttle et al. and L. Morrow et al.; via APS Physics) Read the full article

Ciliary Pathlines

For tiny creatures, swimming through water requires techniques very different than ours. Many, like this sea urchin larva, use hair-like cilia that they beat to push fluid near their bodies. The flows generated this way are beautiful and complex. (Image credit: B. Shrestha et al.) Read the full article

Ice Damages With Liquid Veins

Water expands when it freezes, a fact that's often blamed for ice-cracked roads. But expansion isn't what gives ice its destructive power. In fact, liquids that contract when freezing also break up materials like pavement and concrete. (Image credits: pothole - I. Taylor, experiment - D. Gerber et al.; research credit: D. Gerber et al.; via APS Physics) Read the full article

Dancing to Chopin

Droplets of paint whirl to Chopin's "Nocturne Op. 9 No. 2" in this short film from artist Thomas Blanchard. The glitter particles in the paints act as seed particles that highlight the flow within and around each drop.  (Image and video credits: T. Blanchard; via Colossal) Read the full article

Inside a Zebrafish Heart

This glimpse inside a 5-day-old zebrafish's heart shows why they're often used as a model organism in cardiac studies. The fish's heart rate is similar to humans and its two-chamber heart -- one atrium and one ventricle, both seen here -- serves as a simplified version of ours. (Video credit: M. Weber/2023 Nikon Small World in Motion Competition) Read the full article

Granular Gaps

Push air into a gap filled with a viscous fluid, and you'll get the branching, dendritic pattern of a Saffman-Taylor instability. Here, researchers use a similar set-up: injection into a narrow gap between transparent planes to explore something quite different. (Image and research credit: D. Zhang et al.; via Physics Today) Read the full article

Test Firing a Rocket Engine

Watching a rocket engine start up in slow motion is always fun. This Slow Mo Guys video shows a test fire of one of Firefly's engines, which is capable of 45,000 pounds of thrust. (Video and image credit: The Slow Mo Guys) Read the full article

The Jumping Jump

Turn on your kitchen sink, and the falling jet may form a circle of shallow flow where it strikes the sink. This fast-moving region of flow, surrounded by a wall of water, is a hydraulic jump.  (Image credit: sink - Nik, jump - A. Goerlinger et al.; research credit: A. Goerlinger et al.; via APS Physics) Read the full article

"Emerald Roots"

As charged particles from the solar wind bombard the upper atmosphere, a glowing plasma forms and dances in the sky. The green light of the plasma reflects off moistened sand, rippled by the passage of wind and tide.  (Image credit: L. Tenti; via 2023 Astronomy POTY) Read the full article

Swedish Egg Coffee

In the mid-1800s, Scandinavian immigrants settling in the Midwest had no filters, no percolators, and no drip coffee makers to aid their quest for a cup of coffee. Instead, they used eggs to boil a smooth, grit-free cup.  (Image credit: K. Tomlinson; via Atlas Obscura; submitted by Richard B.) Read the full article

Turbulent Thermal Convection

In the winter, warm air rises from our floor vents or radiators, creating a complex, invisible flow in the background of our lives. Buoyancy lifts warmer air upward while cooler, denser air sinks back down. This thermal convection is everywhere: in our buildings, the ocean, the sky overhead -- even in the visible layer of our sun. (Image credit: A. Blass; research credit: D. Lohse and O. Shishkina in Physics Today) Read the full article

A Working Wirtz Pump

In the mid-eighteenth century, pewterer Andreas Wirtz invented a spiral pump. Even today, his design is useful for small-scale, low-power pumping, as seen in this Steve Mould video.  (Video and image credit: S. Mould) Read the full article

Enhancing the Cheerios Effect

The Cheerios in your morning cereal clump together with one another and the bowl's wall due to an attractive force caused by the curvature of their menisci. A recent study looks at how this effect changes when you're pulling objects out of the liquid. (Image credit: Cheerios - D. Streit, experiment - H. Bense et al.; research credit: H. Bense et al.; via APS Physics) Read the full article

"A Sun Question"

The sun's surface and atmosphere are endlessly dynamic, with magnetic lines, plasma, and convection creating a constant churn. In this photo by astrophotographer Eduardo Schaberger Poupeau, a curving question-mark-like filament appears above the sun's surface. (Image credit: E. Poupeau; via 2023 Astronomy POTY) Read the full article

Swirling Sea Ice

The Sea of Okhotsk is the northern hemisphere's southernmost sea that seasonally freezes. Caught between the Siberian coast and the Kamchatka Peninsula, cold air from Siberia helps freeze water kept at lower salinity due to freshwater run-off.  (Image credit: W. Liang; via NASA Earth Observatory) Read the full article

Jamming Inside

Worm-like Spirostomum ambiguum are millimeter-sized single-cell organisms that live in brackish waters. In milliseconds, these cells can retract to half their original length, generating g-forces greater than a Formula One driver experiences when cornering. How, researchers wondered, do these cells avoid shredding their internal structure with forces that strong? (Image and research credit: R. Chang and M. Prakash; via APS Physics) Read the full article

Do Droughts Worsen Floods?

In recent years many areas have seen record droughts followed by sudden, massive rainfalls. Such wild swings raise the question: does drought-parched soil make flooding worse? That's the question Grady tackles in this Practical Engineering video, and, as is often the cause in real-world engineering, the answer is complicated. (Video and image credit: Practical Engineering) Read the full article