Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Air Pressure in Flight
We live at the bottom of a sea of air, surrounded by a constant pressure equal to 101 kPa (14.7 psi) over our entire bodies. For the most part, we don’t notice the pressure air exerts on us. But if you’ve flown on a commercial airplane, you may have noticed some of the effects of…
Sharkskin Instability
Homemade spaghetti noodles exhibit a roughened surface that’s the result of viscoelastic behavior known as the sharkskin instability. It’s usually observed in the industrial extrusion of polymer plastics. In the case of spaghetti, the long, complex polymer molecules necessary for the instability come from the proteins in eggs. The characteristically rough surface of the extruded…
Making Lava
In this video, NPR’s Adam Cole takes a trip to upstate New York to find out how to make lava – and not the kind with vinegar and baking soda! We’ve featured footage from this duo before. Since most lava flows don’t occur in predictable or controlled circumstances, it can be tough for scientists to…
“En Plein Vol”
Artist Antoine Terrieux’s “En Plein Vol” exhibit shows off the power of hair dryers. Parts of the exhibit, like the floating ball at 0:16, rely on Bernoulli’s principle and the moving stream of air the dryers generate. Others, like the smoke tornado at 0:39 or the (suspended) paper airplane at 0:56, use the hair dryers…
Spinning Paint
Fluid dynamical behaviors are often the result of competing forces. Here paint flung from a spinning rod illustrates the effects of adhesion, surface tension, and centrifugal force. In general, surface tension tries to hold a fluid together, and adhesion allows it to stay attached to a surface. Centrifugal force, on the other hand, tends to…
Underwater Explosions
As dangerous as explosions are in air, they are even more destructive in water. Because air is a compressible fluid, some part of an explosion’s energy is directed into air compression. Water, on the other hand, is incompressible, which makes it an excellent conductor of shock waves. In the video above we see some simple…
Bubble Rupture
Surface tension draws bubbles into spheres, but the balance of forces holding the sphere together is delicate. When pierced by a projectile, sometimes soap films can heal themselves, but often the film ruptures. Once a hole forms in the bubble, the film’s integrity is lost. Instead of holding the bubble together, surface tension pulls the…
Calbuco
Filmmaker Martin Heck captured incredible timelapse footage of the Chilean volcano Calbuco erupting earlier this year. Fluid dynamics on these enormous geophysical scales is always awe-inducing. In the beginning, clouds bob gently and flow around the landscape. Then the volcano erupts, and the towering ash cloud of the eruption roils with turbulence, displaying eddies with…
Water in Oil
Pouring water on an oil fire is a quick way to cause almost explosive results. Since water is denser than oil, it quickly sinks to the bottom of a container, heating up as it does. When the water reaches its boiling point, it evaporates and expands as steam. That phase change involves a huge change…
Sea Foam
Photographer Lloyd Meudell captures surrealistic images of breaking sea foam. Interestingly, the sea foam is essentially a three-phase fluid made up of air, water, and sand. Yet despite the surrealism of its forms, the foam bears strong resemblance to other flows. The shapes the foam forms are reminiscent of vibrated non-Newtonian fluids like paint or…