FYFD

Tag: physics

  • Splashy Heroines

    Splashy Heroines

    In his latest work, photographer Jaroslav Wieczorkiewicz used splashing liquids to create fantastical superheroine costumes. The splashes are all real, composited together in post-production from hundreds of individual splashes. He uses cold whole milk as his base liquid, sometimes supplementing with dye or paint for color. There’s also a behind-the-scenes video showing how the pictures are made, but, fair warning, it’s in German with some English subtitles and does contain nudity (link). (Image credits: J. Wieczorkiewicz; via Gizmodo)

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    Growing Snowflakes

    It’s easy to miss the beauty of a snowflake if you don’t take a close look. These tiny crystals form when water freezes onto a dust particle or other nucleation site, and they grow as water vapor freezes on to the nucleus. The structured appearance of a snowflake comes from the bonds formed between water molecules, but the exact type and shape of crystal formed–not all snowflakes are six-sided!–depends on the local temperature and humidity during freezing. This microscopic timelapse video by Vyacheslav Ivanov lets you watch the process in action. (Video credit: V. Ivanov; via io9)

  • Viscous Droplet Impacts

    Viscous Droplet Impacts

    Viscosity can have a notable effect on droplet impacts. This poster demonstrates with snapshots from three droplet impacts. The blue drops are dyed water, and the red ones are a more viscous water-glycerol mixture. When the two water droplets impact, a skirt forms between them, then spreads outward into a sheet with a thicker, uneven rim before retracting. The second row shows a water droplet impacting a water-glycerol droplet. The less viscous water droplet deforms faster, wrapping around and mixing into the other drop before rebounding in a jet. The last row switches the impacts, with the more viscous drop falling onto the water. As in the previous case, the water deforms faster than the water-glycerol. The two mix during spreading and rebound slower. In the last timestep shown, the droplet is still contracting, but it does rebound as a jet thereafter. (Image credit: T. Fanning et al.)

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    “Marco Polo” Theme

    Netflix’s new original series “Marco Polo” has a distinctive and fluidsy title sequence. The artistic team at the Mill created the effect by painting  images in water atop dense paper before introducing Japanese sumi-ink. Using high-speed photography, they filmed the diffusion of the ink into the water as it reveals the larger picture. There’s a great behind-the-scenes break down and video over at their blog. (Video credit: The Mill, submitted by jshoer)

  • Propagating Flames

    Propagating Flames

    Like many flows, flames can be unstable and undergo a transition from orderly laminar flow to chaotic turbulent flow. The timelapse image above shows the propagation of a flame front travelling downward. Each blue line represents the forwardmost position of the flame at a specific time. The flame is essentially two-dimensional, held between two glass plates separated by a 5-mm gap. The V-like points in the flame front are called cusps, and if you look closely, you can see cusps forming and even merging as the flame moves downward. Also notice how the flame front is more uniform near the top of the image, but, by the bottom, it has split into many more cusps. This is one of the indications that the flame is unstable. Check out the full poster-version of the image in the Gallery of Fluid Motion. (Photo credit: C. Almarcha et al., original poster)

  • Stepping on Lava

    Stepping on Lava

    What happens when you step on lava? (First off, don’t try this yourself.) Lava is both very dense and very viscous, so, as illustrated in the animation above, it does not give all that much under pressure. If you were to fall on it, you’d land, sink a little bit, and then get burned. It’s also interesting to note that the lava springs back after being indented. Basaltic lava like that found in Hawaii, where this clip originates, does have viscoelastic properties, which might explain the elasticity of the deformed fluid. (Image credit: A. Rivest, source video; via Gizmodo)

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    Simplified Schlieren Set-up

    Schlieren photography offers a glimpse into flows that are usually invisible to the human eye. With a relatively simple set-up–a light source, collimating mirror(s), and a razor blade–it becomes possible to see differences in density. The technique lets one visualize temperature-driven flows like the buoyant convection from a flame or other heat source, and it can also be used to visualize shock waves and sound. The video above has several neat schlieren demos, including some non-air examples using hydrogen (lighter than air) and sulfur hexafluoride (denser than air), both of which are transparent to the naked eye.  (Video credit: Harvard University, via Jennifer Ouellette)

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    Foggy Canyon

    Timelapse photography reveals the tide-like motions of fog that filled the Grand Canyon last week. This unusual meteorological condition was created by a temperature inversion. Usually air near the ground is warmest and the atmosphere cools as the altitude increases. But occasionally a mass of warm air will trap a layer of cooler air beneath it. In the case of the Grand Canyon, cool foggy air was capped by a warmer air mass, resulting in a sea of fog. Depending on the conditions, temperature inversions can create other distinctive weather patterns like cloud streets or even supercell thunderstorms. (Video credit: Vox; via Flow Visualization)

  • Jumping Droplets

    Jumping Droplets

    When droplets on a superhydrophobic surface coalesce with one another, they jump. Individually, each drop has a surface energy that depends on its size. When two smaller droplets coalesce into a larger drop, the final drop’s surface energy is smaller than the sum of the parent droplets. Energy has to be conserved, though, so that excess surface energy gets converted to kinetic energy, causing the new droplet to leap up. Smaller droplets have higher jumping velocities. For more, see the original video. (Image credit: J. Boreyko and C. Chen, source video)

  • Phytoplankton Flow Viz

    Phytoplankton Flow Viz

    Nutrient-rich waters off Patagonia in South America blossom with phytoplankton in this satellite image. When present in large quantities, these microscopic photosynthesizers lend a green hue to the water. They act as seed particles in the flow, highlighting the currents and flow that carry them. If you check out the full resolution version of the photo, you can admire the rich detail in the whorls of ocean mixing. There even seem to be Kelvin-Helmholtz-like instabilities creating trains of vortices along the interface between separate bands. (Photo credit: NASA/ASU; via SpaceRef; submitted by jshoer)