This award-winning aerial image by photographer Stuart Chape shows a tidal creek in Lake Cakora, New South Wales, Australia. At first glance, it looks much like any river delta, with branching dendritic paths that split into smaller and smaller waterways. That’s deceptive, though, because very different forces shape this creek. Because tides move in and out, a tidal creek is home to flows that move both directions — toward and away from the branches. That also means that flow speeds can change rapidly as the tides shift, which in turn changes which sediments get lifted, dropped, and moved around the creek bed. (Image credit: S. Chape/IAPOTY; via Colossal)
Tag: branching flow
Why Nature Loves Fractals
Trees, blood vessels, and rivers all follow branching patterns that make their pieces look very similar to their whole. We call this repeating, self-similar shape a fractal, and this Be Smart video explores why these branching patterns are so common, both in living and non-living systems. For trees, packing a large, leafy surface area onto the smallest amount of wood makes sense; the tree needs plenty of solar energy (and water and carbon dioxide) to photosynthesize, and it has to be efficient about how much it grows to get that energy. Similarly, our lungs and blood vessels need to pack a lot of surface area into a small space to support the diffusion that lets us move oxygen and waste through our bodies. Non-living systems, like the branches of viscous fingers or river deltas or the branching of cracks and lightning, rely on different physics but wind up with the same patterns because they, too, have to balance forces that scale with surface area and ones that scale with volume. (Video and image credit: Be Smart)
Fediverse Reactions
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Siberia’s Lena River Delta
As rivers near the sea, they often slow down and branch out, creating intricate paths through delta wetlands. This video explores the Arctic’s largest river delta, that of the Lena River in Siberia, during its spring and summer flood season. The images were all taken by satellite and processed with color enhancements to highlight patterns in the water. Although this is not quite how the area would appear by eye, all of the visible patterns are real. (Image credit: N. Kuring/NASA’s Ocean Color Web; video credit: K. Hansen; via NASA Earth Observatory)
Branching Light with Soap Bubbles
By shining laser light through soap bubbles, researchers have demonstrated branching flow in light for the first time. This branching occurs when waves travel through a disordered medium where the typical size of the disordered regions is larger than the wave’s length. Previously, scientists had seen evidence of this phenomenon in electrons, sound waves, and even ocean waves.
Soap bubbles serve as an excellent platform for branching in light because their exceptionally thin film varies in thickness thanks to the interplay of buoyancy, Marangoni effects, and evaporation. It’s also comparable to — but still slightly larger than — the wavelength of light. The experiment is far from simple, though. Lining the laser up with the soap bubble is tough, especially when your bubble is likely to pop! (Video credit: Nature; research credit: A. Patsyk et al.; submitted by Kam-Yung Soh)
