Wet fur forms a spiral of spiky hairs in this image by photographer Ben Dalgleish. For thin and flexible fibers like hair, a little moisture lets them clump together, forming stiffer (but still flexible) shapes. The technical term for this water-meets-flexible-solid phenomenon is elastocapillarity, and it lets you do things like wind a wire with a bubble. It also makes a big difference when washing hair, including in space. (Image credit: B. Dalgleish/BWPA; via Colossal)
Fabrics flutter in seemingly impossible ways in artist Thomas Jackson‘s images. But despite first appearances, each photograph is true to life; the fabrics are suspended on taut lines. Their dance is driven by wind energy, drag, tension, and flow–not manipulated pixels. I love the (turbulent) energy of them! (Image credit: T. Jackson; via Colossal)
Flow visualization is both an art and science in fluid dynamics. Here, researchers were interested in studying the separation bubble that forms over a backward-facing ramp–a shape that shows up, for example, on an aircraft. In these areas, the flow over the surface separates, leaving an unsteady, recirculating bubble.
That’s the flow that researchers are visualizing here. They’ve done so by adding tiny helium-filled soap bubbles to the flow. With bright lights illuminating the bubbles, each one leaves a streak in a photograph, showing where the bubble moved during the time the camera’s shutter was open. Although images like these are beautiful, they can also be analyzed by computers to extract the underlying flow that created the image. (Image and research credit: B. Steinfurth et al.; see also here)
Photographer Jan Erik Waider is a master of capturing incredible landscape imagery. In these videos, he uses a drone to film waves in the Baltic Sea gently undulating polygonal slabs of ice on the ocean surface. The interplay of light, color, and motion looks almost surreal, but nature is better than we credit at making imagery too good to look away from. (Video and image credit: J. Waider/NorthLandscapes; via Colossal)
When flow moves past a cylinder, vortices get shed in its wake. Known as a von Karman vortex street, this distinctive pattern is seen behind flags, islands, and even behind starships. Here, researchers are simulating flow of a viscoelastic fluid, where–unlike water or other Newtonian fluids–elastic stresses can build up.
As the flow hits the leading edge of the cylinder, the polymers in the fluid compress and then get stretched as the flow moves around the cylinder. The left image shows vorticity in the flow; the right shows elastic stresses. The large swirls are primary vortices–those shed off the cylinder. But look closely and you’ll see smaller secondary vortices curled up beside the primaries. These form when the elastic stresses in the fluid pull some of the shear layer into the wake. (Image and research credit: U. Patel et al.)
Photographer Chris Perani is fascinated by the microstructures of insect wings, which he captures in “extreme macro” through focus stacking–letting us see wings in glorious micron-scale detail. In addition to giving insects their brilliant colors and irridescence, these structures serve another key role: they help insects stay dry. In a world where contact with water is unavoidable, insects have instead evolved to trap air in the gaps of their wings, letting water slide off instead of sticking. (Image credit: C. Perani; via Colossal)
A toad swims across a pond in this award-winning image from photographer Paul Hobson. The shot was actually captured from below the water, with the camera kept dry in a glass housing. Although the frog appears to be mid-leap, the light-distorting ripples around its feet hint at the flow its kick generated. It’s reminiscent of the vortices left by water striders as they move. (Image credit: P. Hobson/BWPA; via Colossal)
A slight change in perspective can do wonders. In this video, the Slow Mo Guys look at a burning flame from below. They accomplish this by mounting a gas grill upside-down. This small change means that buoyancy can’t simply lift heat and exhaust gases away from the flame source. Instead, the flow pushes out and around the edges of the grill.
The views are, as always, amazing. The billowing flames are mesmerizing–often closer to laminar than turbulent. And the added spectacle of cinnamon combusting in the later segments really does make for the kind of visuals you’d expect in a sci-fi movie. (Video and image credit: The Slow Mo Guys)
Meltwater braids like a river delta in this gorgeous image from photographer Stuart Chape. It earned the Silver distinction from the World Nature Photography Awards in their “Planet Earth’s landscapes and environments” category. Water takes tortuous paths like these as it tries to balance the local incline, erosion, deposition, and flow rate. (Image credit: S. Chape/WNPA; via Colossal)
Light shines dimly through the wall of an ice cave in this photograph by Marie-Line Dentler. Shaped by melting, pressure, freezing, and fracture, these structures are dynamic and ethereal. (Image credit: M. Dentler; via Colossal)
