Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Superwalking Droplets
Vibrate a pool of silicone oil and you can generate walking droplets. Drive the vibration at two simultaneous frequencies and you can support much larger droplets, known as superwalkers. These superwalkers have their own intriguing dynamics, a few of which are featured in this video. Superwalkers can create promenading pairs, chase one another, orbit, and…
Morphing Wings Using Real Feathers
Although humanity has long been inspired by bird flight, most of our flying machines are nothing like birds. Engineers have struggled to recreate the ease with which birds are able to morph their wings’ characteristics as they change from one shape to another. Now researchers have built a biohybrid robot, PigeonBot, that uses actual pigeon…
Breaking the Euler Equations
Mathematicians like to break things. Or, more exactly, they like to know when the equations we use to describe physics break down. One popular target in fluid mechanics are the Euler equations, which describe the motion of frictionless, incompressible flows. Mathematicians have been on the hunt for centuries for situations where these equations predict singularities,…
When the Mediterranean Dried Up
Geological evidence shows that millions of years ago, the Mediterranean Sea nearly dried out. In fluid mechanics, we’d describe this problem using one of our fundamental equations: conservation of mass, also known as continuity. Imagine a volume containing the entire Mediterranean. To describe the amount of sea water in that volume, you need to keep…
Captured by Waves
Acoustic levitation and optical tweezers both use waves — of sound and light, respectively — to trap and control particles. Water waves also have the power to move and capture objects, as shown in this award-winning poster from the 2019 Gallery of Fluid Motion. The central image shows a submerged disk, its position controlled by…
Rattlesnakes Sip Rain From Their Scales
Getting enough water in arid climates can be tough, but Western diamondback rattlesnakes have a secret weapon: their scales. During rain, sleet, and even snow, these rattlesnakes venture out of their dens to catch precipitation on their flattened backs, which they then sip off their scales. Researchers found that impacting water droplets tend to bead…
Bouncing Off Defects
The splash of a drop impacting a surface depends on many factors — among them droplet speed and size, air pressure, and surface characteristics. In this award-winning video from the 2019 Gallery of Fluid Motion, we see how the geometry of a superhydrophobic surface can alter a splash. When a drop falls on a protruding…
Superman’s Hair Gel
I love a good tongue-in-cheek physical analysis of superheroes. This estimate of the drag force experienced by Superman’s hair when outracing a plane or speeding bullet was done by Cornell students. According to their calculations, Superman’s hair (or his hair gel) must withstand nearly 80,000 Newtons of force. That’s a bit less than the typical…
A Dance of Hydrogen Bubbles
Hydrogen bubbles rise off zinc submerged in hydrocholoric acid in this short film from the Beauty of Science team. In high-speed video, the rise of the bubbles is stately and mesmerizing. Notice how the smallest bubbles appear as perfect spheres; for them, surface tension is strong enough to maintain that spherical shape even against the…
Tapping a Can Won’t Save Your Beer
It happens to the best of us: sometimes our beer gets shaken up during transit. One common reaction to this is to tap the side of the can repeatedly before opening, but a new scientific study shows that tapping doesn’t affect the volume of beer lost. Danish scientists tested over 1,000 cans of beer in…