Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Breaking the Wave Speed Limit
Whirligig beetles are small surface swimming insects. As they race across the water surface, they create both visible and unnoticeable waves on the water. These waves are the result of both surface tension and gravity. Typically, it’s the wavelength of the gravity waves that limit a swimmer or boat’s speed. When the wavelength of the…
How Jet Engines Work
Jet engines are a major part of aviation today, and this great video from the new LIB LAB project breaks down how jet engines operate. It focuses especially on the subject of combustion, in which fuel-air mixtures are burned to generate power and thrust. By breaking fuels down into simpler compounds, jet engines are able…
Supporting Bubbles
Surface tension holds small droplets in a partial sphere known as a spherical cap. But when droplets become larger, they flatten out into puddles due to the influence of gravity. In contrast, soap bubbles remain spherical to much larger sizes. The bubble pictured above, for example, is more than 1 meter in radius and nearly…
Spillways
Extensive rains in California have brought an unusual sight to Lake Berryessa – an overflowing spillway. The upper photo, taken in 2010, shows the concrete structure of the spillway’s entrance, known as a bellmouth – or, in the words of locals, a glory hole. When the water level rises above the concrete, water begins to…
Battery Rockets
When I post Slow Mo Guys videos, it often comes with a warning not to try this at home. For their latest video, that deserves an extra-special mention: seriously, don’t try this. In this video, Dan and Gav explode lithium-ion batteries. In the process, they discover a safety feature – namely vents on one face of…
Wrinkling Winds
If you’ve ever sat out on a lake and just watched the water’s surface, you’ve probably noticed how complex and variable it looks. There may be waves that rock your kayak but there are smaller variations, too, like little ripples or even tiny wrinkles that appear on the surface. Much of this activity comes from…
Aerodynamic Leidenfrost Effect
If you place a droplet on a surface much hotter than its boiling point, that droplet will skitter and float almost frictionlessly across the surface on a thin layer of its own vapor. This is what is known as the Leidenfrost effect. But you don’t have to heat a surface to get this behavior. There’s…
An Octopus’ Handshake
Cephalopods, especially octopuses, are fascinating creatures. At sea level, an octopus can generate an impressive pressure differential of 1 to 2 atmospheres with each of its suckers. That incredible grip is possible thanks to fluid dynamics. An octopus’s sucker consists of two main parts: the ring-shaped infundibulum on the outer surface and the inner, cup-shaped acetabulum.…
Vortex Impact
When a vortex ring impacts a solid wall (or a mirrored vortex ring), it expands and quickly breaks up. The animations above show something a little different: what happens when a vortex ring hits a water-air interface. As seen in the side view (top image), the vortex starts to expand, but its shear at the…
Breaking Soon
Australian photographer Warren Keelan captures spectacular photos of waves just before and during the moment they break. Fluid dynamics is defined by motion – specifically the motion of substances that do not hold a single form – but one thing I love about wave photography is how crisp and solid water appears when frozen in…