When excited, a group of particles can behave much like a gas. These granular gases exhibit many similarities to molecular gases but contain one vital difference: without a constant input Keep reading
Tag: granular material
Shear in Shaken Sands
The dynamics inside a shaken granular material, like sand, are fascinatingly complex. In this study, researchers used x-ray radiograms to peer inside a horizontally-shaken container of sand. They found that Keep reading
Digging Droplets
A droplet on a surface much hotter than its boiling point will skate on a layer of its own vapor, thanks to the Leidenfrost effect. But if that surface is, Keep reading
Scaling High-Speed Impacts
The impact of a solid object into a bed of grains is a major topic in many fields from ballistics to astronomy. Researchers study these impacts experimentally using photoelastic disks, Keep reading
Colorful Tides
This false-color satellite image — the recent winner of NASA Earth Observatory’s Tournament Earth 2020 — shows sands and seaweed off the coast of the Bahamas. Ocean currents and tides Keep reading
Unifying Sediment Transport Theory
On windy days, streaks of snowflakes snake in the air above a mountaintop snowfield. And when snorkeling in the surf, you can watch the inbound waves sculpt underwater ripples in Keep reading
Breaking Up Granular Rafts
Particles at a fluid interface will often gather into a collection known as a granular raft. The geometry of the interface where it meets individual particles, combined with the surface Keep reading
Dunes Avoid Collisions
The speed at which a dune migrates depends on its size; smaller dunes move faster than larger ones. That speed differential implies that small dunes should frequently collide into and Keep reading
The Sand Sea’s End
The northern extent of Africa’s Namib Sand Sea ends where the reddish dunes meet the Kuiseb River and the hard, rocky land on its other side. Within the sand sea, Keep reading
In Search of a Better Espresso
Of specialty coffee drinks, espresso has the most cup-to-cup variation in quality. For those who are not coffee aficionados — such as yours truly — espresso is made by forcing Keep reading