Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
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Fluid Chains
In this video, Steve Mould tackles a question many of us have likely wondered: just why does falling water make this chain-like shape? When pouring from a slit-like orifice, water jets take on this undulating pattern. While I have no issue with Steve’s explanation of surface tension oscillations driving the shape, I’ll quibble a little…
Meltwater Tracking Via Seal
Monitoring meltwater from Antarctic glaciers is critical for understanding our changing climate, but such remote and inaccessible regions are tough to collect data in. So researchers are turning to local workers to help them gather data. By collecting and analyzing data from seal tags, researchers have mapped new seasonal variations in meltwater flows around Pine…
Superior Mirage
This photograph of a ship seemingly floating far above the water is not some Photoshop fakery; it’s physics creating the illusion. It’s an example of what’s known as a superior mirage — superior because the mirage appears above the object’s actual location, unlike the mirages you see above the road on a hot day. In…
“Dancing With Danger”
Filmmaker Chris Bryan captures surfer Kipp Caddy as he rides an enormous wave in “Dancing With Danger.” Nothing quite captures the majesty of these powerful flows like high-speed videography. Enjoy the break, the spray, and those awesome rib vortices. (Image and video credit: C. Bryan)
Jumping Frost
Liquid water is easily electrically charged, due to its polar nature. That’s why rubbing a comb is enough to deflect a stream of water. Ice is harder to charge, but it can happen, especially when there are temperature gradients across the ice. That’s the key behind this study of jumping frost. When ice crystals grow…
Taylor Columns
When rotating, fluids often act very differently than we expect. For example, an obstacle in a rotating flow will deflect flow around it at all heights. This is known as a Taylor column. In this video, we see the phenomenon recreated in a simple rotating tank (that’s easy to build yourself). Once all the water…
Freezing Splats
In fluid physics, there’s often a tug of war between different effects. For droplets falling onto a surface colder than their freezing point, the hydrodynamics of impact, sudden heat transfer, and solidification processes all compete to determine how quickly and in what form droplets freeze. The images above form a series based on changing the…
Fallstreak Holes
Occasionally clouds appear to have a hole in them; these are known as fallstreak holes or hole-punch clouds. To form, the water droplets in the cloud must be supercooled; in other words, they must be colder than their freezing point but still in liquid form. When disturbed — say, by the temperature drop caused by…
“Radiolarians”
“Radiolarians” is a short film by artist Roman De Giuli using ink, alcohol, and oil. Much of the fluid motion involves break-up into droplets. The effects appear to rely heavily on Marangoni bursting, the physics of which you can learn about in this previous post. (Image and video credit: R. De Giuli)
Chaotic Mixing in Porous Media
One of the peculiar characteristics of viscous, laminar flows is that they are reversible. Squirt dye into glycerin, stir it one way, then the opposite direction, and the dye returns to its initial position. But this neat trick only works in simple geometries; in a more complex environment, like the pores between packed gravel, flows…