Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
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The Fluid Dynamical Sewing Machine
If you’ve drizzled viscous liquids like honey or syrup, you’ve no doubt witnessed their ability to coil. Combine that coiling with a moving platform and you form a system known as the fluid dynamical sewing machine, which creates different consistent patterns of loops and curves depending on the speed at which the liquid falls and…
Spinning Droplet Galaxies
Water flung from a spinning tennis ball takes on a shape reminiscent of a spiral galaxy. As it detaches, water leaves the surface with both the tangential velocity of the spinning ball and a radial velocity due to the centrifugal force flinging it. The continued spin of the ball makes the thin ligaments of water…
Flying Backwards
Spend a summer afternoon floating in a kayak and chances are you’ll see some impressive aerial acrobatics from dragonflies. One of the dragonfly’s superpowers is its ability to fly backwards, which helps it evade predators and take-off from almost any orientation. To do this, the dragonfly rotates its body so that it is nearly vertical,…
Craters and Rays
The history of our solar system is written in impact craters, but these craters have been remarkably mysterious for years. Scientists knew that you could recreate many of their features by dropping solid objects into granular materials like sand, but this did not produce the distinctive rays that we see around many real craters (bottom…
Lava Balls
View this post on Instagram #LeilaniEstatesEruption #KilaueaVolcano LATEST (June 27 at 8:15 PM): New unbelievable video from @IkaikaMarzo captures the phenomena that USGS has named a “lava boat”. Watch as it makes its way down the #Fissure8 lava river in Kapoho and then breaks apart ? • Dear @kalapanaculturaltours, I thought lava boats were for…
Vortex Ring Collisions
One of the most enduringly popular submissions I receive is T. Lim’s experimental footage of two vortex rings colliding head-on. It’s an devilishly tough experimental set-up to master because perfectly aligning the rings is incredibly difficult. The pay-off, however, is huge because the breakdown of the colliding rings and their transformation into secondary rings is…
2D Turbulence
Turbulence, the chaotic regime of fluid dynamics, is a complicated beast. It’s hard to analyze or predict, but we do understand some general ideas about it, like the fact that energy starts out in large eddies, cascades down smaller and smaller ones, and finally gets dissipated at the smallest scales, where viscosity snuffs them out.…
Visualizing Turbulence
Turbulence, the seemingly random and chaotic state that fluids often tend toward, can be difficult to wrap one’s head around. Turn your faucet on high or pour milk into your coffee, and the flow just looks like a completely unpredictable mess. But there are important patterns to be found.These flows have many different lengthscales and…
Star Wars Aerodynamics
Science fiction is not always known for hewing to scientific fact, so it will probably come as little surprise that Star Wars’ ships have terrible aerodynamics. But it’s nevertheless fun to see EC Henry’s analysis of drag coefficients of various Rebel and Imperial ships and just how poorly they fare against our own designs. Drag…
Glorious Vortex Street
Satellite imagery often reveals patterns we might struggle to see from the ground. Here Gaudalupe Island off the western coast of Mexico perturbs the atmosphere into a series of vortices. Air flowing across the open ocean gets deflected around and over the rocky, volcanic island, creating a line of vortices that get shed off one…