FYFD

Tag: siphon

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    What Limits a Siphon

    Siphons are a bit mind-boggling for anyone who has internalized the idea that water always flows downhill. But gravity actually allows a siphon’s water to flow up and over an obstacle, provided certain conditions are met. Steve Mould digs into the details of those conditions in this video, where he searches for the maximum height a siphon can reach.

    A quick note on terminology: Steve explains that the siphon breaks when water near the top starts “boiling.” Other sources may use the term “cavitating” for this sudden phase change. There’s not–to my knowledge–a generally-agreed-upon definition that clearly distinguishes between boiling and cavitation in this situation. Whichever term you use, the water in the siphon doesn’t care; either way, it’s experiencing a local pressure that’s so low that it switches from a liquid state (where it can resist tensile forces) to a gaseous one (where it cannot resist tension). (Video and image credit: S. Mould)

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    The Incredible Engineering of the Alhambra

    Begun in 1238, Alhambra Palace in Grenada, Spain is a monument to Islamic architecture and clever engineering. Despite sitting far above the city, the Alhambra was fed by the river, diverted from upstream along a canal. Within the palace itself, this water was used for heated flooring, steam rooms, baths, and even a fountain that told the time. This Primal Space video breaks down how engineers pressurized the water lines, moved water into and around the palace, and how wonders like the palace’s fountains worked. As impressive as the engineering is, though, it’s worth remembering that the Alhambra’s engineers were not creating new technologies: multiple older civilizations also used aqueducts, water wheels, and siphons to similar effect. (Video and image credit: Primal Space)

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    Breaking Down a Water-Powered Timer

    In his latest “cutaway” video, Steve Mould takes a look at how you can nest siphons to create a system that periodically flushes itself. This kind of water-powered timer is useful in, say, public restrooms with a urinal system that collectively flushes every once in a while. In the video, Mould talks through each step of the system and some of the challenges he ran into when trying to create a pseudo-2D version of it. As is often the case with these videos, it’s a strangely satisfying process to watch. (Video and image credit: S. Mould)

  • The Intermittent Spring of Afton, WY

    The Intermittent Spring of Afton, WY

    Yellowstone may get top billing, but Wyoming is home to more fluid dynamical wonders, like the world’s largest rhythmic spring. Located a little outside Afton, WY, Intermittent Spring — as the name indicates — runs for roughly 15 minutes, stops for the same length, then starts up again. The leading theory for this periodic flow depends on the siphon effect. Essentially, water runs continuously into a cavern underground, but to get to the surface, it must traverse a narrow tube with a high point that lies above the spring’s eventual exit. When the water level reaches that high point, it creates a siphon, sucking water out of the cavern and making the spring flow. But eventually the water level drops to the point where air rushes in, breaking off the flow until the water level recovers. That’s consistent with the spring’s behavior; it only runs in this intermittent fashion from late summer to fall, when groundwater levels are lower. (Image credit: Wikimedia Commons; video credit: University of Wyoming Extension; submitted by Kam-Yung Soh)

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    Building a Water-Based Computer

    Having previously tackled the “greedy” self-starting siphon, Steve Mould set out to build a water-based computer capable of adding simple numbers. To do this, he had to build logic gates capable of distinguishing concepts like AND and exclusive OR (XOR); the self-starting siphon was critical for this, diverting water down one output or another depending on the TRUE or FALSE result. With a series of water logic gates, he built a simple computer capable of adding numbers in binary. Check out the video to see it all in action! (Video and image credit: S. Mould)

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    The Greedy Cup in Your Washing Machine

    A Pythagorean, or “greedy” cup, is one that automatically drains itself once filled to a certain level. In other words, it’s a self-starting siphon – one that triggers only at certain fill level. And chances are you have an example of this mechanism close at hand: inside your washing machine’s soap tray. That’s why the tray has such a clearly marked maximum fill line; if you were to put more soap than that in the tray, it would automatically drain! (Image and video credit: S. Mould)

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    Self-Started Siphoning

    Here’s a fun activity you can do while you #StayHome: build a self-starting siphon. Michael from VSauce explains how in this video. Moving fluids from one location to another is almost always about pressure, and a siphon is no different. To get the water to flow, there must be unequal pressures driving the liquid to move from high pressure to lower pressure. This is the basic physics behind any siphon; the fun of a self-starting siphon comes from generating enough pressure imbalance to start flow without applying suction. (Video credit: D!NG/M. Stevens)

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    The Pythagorean Cup

    According to legend, Pythagoras invented a cup to prevent his students from drinking too greedily. If they overfilled the cup, it would immediately drain out all the fluid. The trick works thanks to a U-shaped tube in the center of the cup. As long as the liquid level is below the highest point in the U-tube, only the entrance side of the tube will be filled. As soon as the liquid level in the cup is higher, the weight of all that fluid forces liquid up and around the bend. This kicks off a siphoning effect that pulls all the fluid out. Coincidentally, this is the same way that toilet flushing works! Pulling the handle releases extra water into the bowl that raises the fluid level higher than the highest point in a U-bend. That establishes a siphon, which (provided nothing has clogged the pipe), empties the toilet bowl. (Video credit: Periodic Videos)

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    Fluids Round-up

    Here’s to another fluids round-up, our look at some of the interesting fluids-related stories around the web:

    – Above is a music video by Roman Hill that relies on mixing and merging different fluids and perturbing ferrofluids for its visuals as it re-imagines the genesis of life.

    – GoPro takes viewers inside a Category 5 typhoon with 112 mph (180 kph; 50 m/s) winds.

    – Astronaut Scott Kelly demonstrates playing ping pong with a ball of water in space. (via Gizmodo)

    – See fluid dynamics on a global scale with Glittering Blue. (via The Atlantic)

    – To make a taller siphon, you have to find a way to avoid cavitation.

    – Speaking of siphons, Randall Munroe tackles the question of siphoning water from Europa over at What If? (submitted by jshoer)

    – The Mythbusters make a giant tanker implode using air pressure.

    – Sixty Symbols explores how tiny things swim.

    – What happens when you bathe in 500 pounds of putty? Let’s just say that bathing in an extremely viscous non-Newtonian fluid is not recommended. (via Gizmodo)

    (Video credit and submission: R. Hill et al.)

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    Self-Siphoning Stream of Beads

    Pull a bit of a long chain out of a container, and you’ll quickly find the beads take on a life of their own, siphoning out of the jar while leaping and looping in the air. Some of the dynamics are clear – the ever-growing free end of the chain has weight enough to pull the rest of the chain out, much like the pressure difference that drives a siphon. But a lot of the rest of the dynamics are unclear and have generated a lot of discussion. It turns out that the same behavior is observed for chain laid out on a horizontal surface (video links on the right of that page) and even the dynamics of that simpler version of the problem are complex. All part of the beauty inherent in Newton’s second law. (Video credit: Steve Mould/Earth Unplugged; Research credit: J. A. Hanna et al.; submitted by Elin R)