Search results for: “art”

PyeongChang 2018: Ice-Making
When it comes to winter sports, not all ice is created equal. Every discipline has its own standards for the ideal temperature and density of ice, which makes venue construction and maintenance a special challenge. Figure skating, for example, requires softer ice to cushion athletes’ landings, whereas short-track speed skating values dense, smooth ice for racing. The Gangneung Ice Arena hosts both and can transition between them in under 3 hours. Gangneung Oval hosts long-track speed skating and makes its ice layer by layer, spraying hot, purified water onto the rink. This builds up a particularly dense and therefore smooth ice.
The toughest sport in terms of ice conditions is curling, which requires a finely pebbled ice surface for the stones to slide on. Forming those tiny crystals on the ice sheet can only be done at precise temperature and humidity conditions. This is a particular challenge for Gangneung Curling Center due to its coastal location. To keep the temperature and humidity under control at full crowd capacity, officials even went so far as to replace all the lighting at the facility with LEDs! (Image credit: Pyeongchang 2018, 1, 2, 3)
February 21, 2018
PyeongChang 2018: Bobsleigh
In bobsleigh, two- and four-person teams compete across four runs down an ice track. The shortest cumulative time wins, and since typical runs are separated by hundredths of a second, teams look for any advantage that helps them shave time. The size, weight, and components of a sled are restricted by federation rules; for example, teams cannot use vortex generators to improve their aerodynamics. Instead bobsledders work with companies like BMW, McLaren, and Ferrari to engineer their sleds. Both computational fluid dynamics and wind tunnel tests with the actual team in the sled are used to make each sled as aerodynamic as possible. (Image credit: IOC, Gillette World Sports, source)
February 20, 2018
PyeongChang 2018: Snow-Making
These days artificial snow-making is a standard practice for ski resorts, allowing them to jump-start the early part of the season. Snow guns continuously spray a mixture of cold water and particulates 5 or more meters in the air to generate artificial snow. The tiny droplet size helps the water freeze faster and the particles provide nucleation sites for snow crystals to form. As with natural snow, the shape and consistency of the snow depends on humidity and temperature conditions. Pyeongchang is generally cold and dry, so even the artificial snow there tends to be similar to snow in the Colorado Rockies. Recreational skiers tend to look down on artificial snow, but Olympic course designers actually prefer it. With artificial snow, they can control every aspect of an alpine course. For them, natural snowfall is a disruption that puts their design at risk. (Video credit: Reactions/American Chemical Society)
February 19, 2018
PyeongChang 2018: Skeleton
Skeleton, the sliding event in which athletes race down an ice track head first, is a fast-paced and punishing sport. Skeleton racers can reach speeds of 125 kph (~80 mph) during their descents. This is a little slower than the feet-first luge, in part because the skeleton sled runs on circular bars rather than sharp runners.
Body positioning is key in the sport. It’s the athlete’s primary method of steering, and it controls how much drag slows them down. But skeleton runs are brutally taxing; athletes pull 4 or 5g in the turns – more than astronauts experience during a launch! All that jostling means athletes cannot stand more than about 3 trips down the track in a day. To practice positioning without the bone-jarring descent, athletes can work in a wind tunnel. While the wind tunnel provides the aerodynamic equivalent of their usual speed, athletes focus on holding their bodies in the most streamlined position. Some wind tunnels are even able to provide screens that let the athletes see their drag values in real-time, letting them adjust to learn what works best for them. (Image credit: N. Pisarenko/AP, Bromley Sports)
February 15, 2018
PyeongChang 2018: Ski Jumping
No winter sport is more aerodynamically demanding than ski jumping. A jump consists of four parts: the in-run, take-off, flight, and landing. The in-run is where an athlete gains her speed, and to keep drag from slowing her down, she descends in a streamlined tuck that minimizes frontal area. The biggest aerodynamic challenge comes during flight, when the jumper wants to maximize lift while minimizing drag. The athlete spreads her skis in a V-shape and flattens her body, using her hands to adjust her flight. Flying the farthest requires careful management of forces while in the air. Wind plays a major role as well, with headwinds helping athletes fly farther. To compensate, scoring includes a wind factor calculated based on conditions for each jump. (Image credit: B. Pieper, Reuters/K. Pfaffenbach, PyeongChang 2018)
February 14, 2018
PyeongChang 2018: Moguls
Moguls are bump-like snow mounds featured in freestyle skiing competitions and also frequently found on recreational ski courses. Although competition runs are man-made, most mogul fields form naturally on their own. As skiiers and snowboarders carve S-shaped paths down the slope, their skis and snowboards remove snow during sharp turns and deposit it further downhill. Over a surprisingly short amount of time, these random, uncoordinated actions form bumps large enough that they force skiers and snowboarders to begin turning on the downhill side of the bump. That action continues to carve out snow on the uphill side and deposit it downhill, effectively causing the downhill bumps to migrate uphill, as seen in the timelapse animation below. As more moguls form, their motion organizes them into a checkerboard-pattern that moves in lockstep. Observations show that mogul fields can move about 10 meters uphill over the course of a season. Seemingly, the only way to prevent mogul formation on steep slopes is to regularly groom them back to a flat state! (Image credits: J. Gruber/USA Today; J. Huet; D. Bahr; research credit: D. Bahr et al.)
February 13, 2018
PyeongChang 2018: Ice’s Watery Sublayer
The Olympic Charter declares that winter sports must be practiced on snow or ice. Both are frozen forms of water, which despite its ubiquity, is one of the strangest substances around. In addition to its tendency to expand as it freezes, ice is inherently slippery, and no one’s quite certain yet why.
Most people have heard the theory that ice skating is possible due to high pressure melting the ice beneath the narrow blade. But realistically, pressure melting should only work for ice down to about -3.5 degrees Celsius. By contrast, the ideal temperatures for figure skating and ice hockey are -5.5 and -9 degrees Celsius, respectively. Melting due to friction might account for slipperiness a few more degrees below freezing, but it doesn’t explain why ice can be slippery when you’re just standing on it.
When physicist Michael Faraday suggested in 1850 that ice has a thin liquid-like layer at its surface, many discounted the theory. But modern experimental techniques and computer simulations have shown that Faraday was right. Ice has a liquid-like layer some 1 to 100 nanometers thick at its surface, and this layer persists to temperatures below -30 degrees Celsius. The process is known as surface pre-melting and what causes it is an area of active research for physical chemists. Current theories include hydrogen bonding and even quantum mechanical effects. (Image credit: AP Photo/B. Armangue; research credit: R. Rosenberg; Y. Li and G. Somorjai; F. Paesani and G. Voth)
This opens FYFD’s two-week series on the physics and fluid dynamics of the Winter Olympics. Stay tuned! – Nicole
February 12, 2018
“Moving Creates Vortices and Vortices Create Movement”
A new interactive installation by the Japanese art collective teamLab uses the movement of visitors to drive vortex motion. Entitled “Moving Creates Vortices and Vortices Create Movement,” the installation uses projectors in a mirror room to create the sensation of an infinite, indoor ocean that’s constantly churned by the paths visitors take. In the absence of motion, the room slowly fades to darkness. The installation is currently in the National Gallery of Victoria in Melbourne, Australia, and will be open until April 15th, 2018. (Image credit: teamLab; via Colossal; submitted by jshoer)
P.S. – Winter Olympic coverage will start on Monday, February 12th! – Nicole
February 9, 2018
Crevasses
Glacial ice is constantly flowing but at speeds we don’t notice by eye. That doesn’t mean there aren’t signs, though! Crevasses, narrow fractures in the ice that may be tens of meters deep, are a sign of those flows. Crevasses form in areas where the ice is under high stress. That could be a spot where the ice is flowing down a steeper incline or a place where multiple ice flows merge. Researchers can even use ice-penetrating radar to locate buried crevasses deep inside the ice. These are remnants of past flow conditions and provide hints at how the ice flows have changed over time. Crevasses are also a path for meltwater to penetrate deep into the ice, which can change slip conditions at the base of the glacier and increase both flow and melt rates. (Image credit: NASA/Digital Mapping Survey; via NASA Earth Observatory)
February 8, 2018
Water Calligraphy
Artist Seb Lester creates calligraphy using ink and water, but not in the way you might expect. After writing in water, the artist applies ink a drop at a time, allowing fluid forces to spread it. There are a few effects at play here. Molecular diffusion – the random motion of molecules – can help two fluids mix, but it’s an extremely slow process. The fast, dramatic spread of ink seen in the video is more likely a Marangoni effect. The water and ink have different surface tensions, creating a gradient in surface tension that depends on the relative concentration of the two fluids. Gradients in surface tension create flow, which is why the ink spreads most quickly when it’s applied in an area that’s pure water. For similar physics, check out maze-solving soaps and the title sequence for “Marco Polo”. (Video and image credit: S. Lester, source; via Gizmodo)
February 6, 2018

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