Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Fluorescent Dancing Droplets
These fluorescent droplets of glowstick liquid jiggle and dance in a solution of sodium hydroxide. Some droplets jitter. Some rotate. And some undergo one coalescence after another. It’s always fun to see how fluid dynamics and chemistry combine! (Image and video credit: Beauty of Science)
Why Slicing Tomatoes Works
Picture it: a nice, ripe tomato. Your not-so-recently sharpened kitchen knife. You press the blade down into the soft flesh and… it explodes. Soft solids – like a tomato – don’t react well to cutting, but they slice just fine. Examining why that’s the case is at the heart of this model. Tomatoes are essentially…
Why Aren’t Trees Taller?
Trees are incredible organisms, with some species capable of growing more than 100 meters in height. But how do trees get so big and why don’t they grow even taller? The limit, it turns out, is how far fluid forces can win over gravity. To live and grow, trees must be able to transport nutrients…
Two Views of Ocean Eddies
Colorful, sediment-laden eddies swirl off the Italian coast in this satellite image. These small-scale eddies — less than 10 km in diameter — can be short-lived and are often difficult to capture in numerical models, but remote sensing can help scientists better understand their impact on oceanic mixing, especially when we capture more than one…
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 the sand soon formed bands of lower density (seen as yellow in the radiogram) near the center of the container. Because these bands show a…
Painting on Water With Ebru
Ebru is the South West Asian art of painting atop water, similar to suminagashi in Japan or paper marbling in European culture. This video takes you inside the studio of Garip Ay, a Turkish ebru artist, letting you observe some of the tools and techniques he uses. Ay’s painting are incredibly dynamic, transforming from one…
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, instead, a granular mixture like this glass powder, the droplet will dig itself a hole. As in the usual Leidenfrost situation, the heat of the…
Flexible Filament Reduces Drag
Most shapes aren’t streamlined for fluid flow. We call these bulky, often boxy shapes, bluff bodies. Above, we see two examples of a bluff body, a flat plate, in a soap film. On the left, the plate sits perpendicular to the soap film’s top-to-bottom flow. Two large, counter-rotating vortices form behind the plate and a…
Ventilation and Respiratory Disease
In 1977, one passenger with the flu infected 38 people onboard a flight with malfunctioning ventilation. In this video, Dianna digs into the physics of respiratory disease transmission and just why ventilation is so key to preventing it. There are three primary modes of transmission for respiratory diseases like influence or SARS-CoV-2: 1) touching an…
Sundews Weaponize Viscoelasticity
In nutrient-poor soils, carnivorous plants like the cape sundew supplement their diets by eating insects. To entice their prey, the cape sundew secretes droplets of sugary water. But unwary insects who land to feed soon find themselves unable to pull away from this viscoelastic liquid. Complex molecules in the fluid grant it elasticity, so when…