Sand is a critical component of many built environments. As most of us learn (via sand castle), adding just the right amount of water allows sand to be quite strong. Keep reading
Tag: shear
Imitating a Cough
Coughing and sneezing create violent air flows in and around our bodies. As that fast air rushes over mucus layers in our lungs, throat, and sinuses, the resulting flow breaks Keep reading
Scooting Droplets
As a child, I always loved watching rain on the windows as I rode in the car. Hemispherical droplets got stretched by the wind flowing over them. But they never Keep reading
Bubble Cleaning
Removing dirt and bacteria from fruits and vegetables is a delicate job; too much force can bruise the produce and hasten spoiling. That’s why fluid mechanicians want to give the Keep reading
Slab Avalanche Physics
Slab avalanches like the one shown here begin after weak, porous layers of snow get buried by fresher, more cohesive snow layers. On a steep slope, the weight of the Keep reading
Stably Jammed
Granular materials like sand, gravel, and medications can become a rigid mass when squeezed or sheared. Even with a relatively loose packing, these materials can jam together to act like Keep reading
Mixing the Immiscible
Immiscible liquids — like oil and water — do not combine easily. Typically, with enough effort, you can create an emulsion — a mixture formed from droplets of one liquid Keep reading
Protecting From Storm Surge
The most dangerous and destructive part of a tropical cyclone isn’t the wind or rain; it’s the storm surge of water moving inland. This landward shift of ocean takes place Keep reading
Sunset Swirls
This gorgeous photograph of Kelvin-Helmholtz clouds was taken in late December in Slovenia by Gregor Riačevič. The wave-like shape of the Kelvin-Helmholtz instability comes from shear between two fluid layers Keep reading
Shear and Convection in Turbulence
In nature, we often find turbulence mixed with convection, meaning that part of the flow is driven by temperature variation. Think thunderstorms, wildfires, or even the hot, desiccating winds of Keep reading