Candy-colored glaze oozes down the sides of Brian Giniewski’s Drippy Pots. These mugs seem like a great way to the start the day with a little happy, fluidsy action! (Image credit: B. Giniewski; via Colossal)
Search results for: “art”
Rising Through Turbulence
Plankton — microscopic creatures with often limited swimming abilities — can face daily journeys of hundreds of vertical meters in the ocean. That’s a daunting prospect for any tiny swimmer. A new mathematical model suggests that plankton can have an easier time of it, though, by riding turbulent currents.
The researchers modeled an individual planktar (singular of plankton) capable of sensing nearby velocity gradients and rotating its body to control its swimming direction. With this simple set of controls, their simulated planktar was able to “surf” turbulent currents, covering vertical distances at twice its normal swimming speed despite its curvy path.
Currently, there’s no direct experimental evidence that plankton do this, but it does seem to make sense of experimenters’ observations. With the model’s results to guide them, experimentalists are looking for microswimmers actively orienting themselves based on turbulence. (Image credit: top – B. de Kort, illustration – R. Monthiller et al.; research credit: R. Monthiller et al.; via APS Physics)
How Gas Pump Nozzles Work
Ever wonder how a gas pump shuts off when the tank is full? You might guess that there’s a sophisticated electronic sensor hidden in there. But there isn’t! Gas pumps use an entirely mechanical technique to sense a full tank and shut off flow, as Steve Mould demonstrates in this video.
There are two key components — one fluid mechanical and one based on mechanical linkages — inside the handle. The part that senses a full tank is a Venturi tube, shown in Image 2. The top section of the Venturi tube contains a constriction, where (incompressible) flow is forced to speed up. That increase in speed creates a drop in pressure, which is reflected by the movement of the water in the curved tube below the constriction.
Notice that when there’s no flow through the top tube, the water level is equal on either side of the lower, curved tube. That means that the outside air pressure (connected to the short arm) equals the pressure in the constriction (connected to the long arm). When air is flowing through the constriction, the water level shifts. The water in the short arm gets pushed down while the water in the long arm gets sucked up. That change means that the air pressure outside the tube is now higher than pressure in the constriction.
I’ll let Steve explain what that means for the gas pump! (Image and video credit: S. Mould)
Flowers Through a Hazy Veil
A smoke-like haze obscures colorful bouquets in these photographs from artist Robert Peek. To achieve the effect, Peek submerges his subjects underwater with white dye that sinks due to its greater density. The wakes traced by the dye are impressively laminar, so the dye must drift rather slowly past each petal. The overall effect is beautifully dream-like. You can find more of Peek’s work on Behance and Instagram. (Image credit: R. Peek; via Colossal)
Mixing the Perfect Batter
In baking, there’s a point when wet and dry ingredients get combined to form the batter (or dough) that eventually becomes a tasty treat. Experienced bakers know that the ratio of wet-to-dry must be just right for the final product. Too dry and the mixture won’t come together; too wet and the final product is a soggy mess.
Mixing liquids and powders is ubiquitous outside the kitchen, too. Ceramics, concrete, laundry detergent, chocolate — all involve this critical step. To understand how these mixtures transition from fluid to clustered granules to granulations (think wet sand), researchers carefully studied a mixture of glass spheres and glycerol. When there were relatively few particles in the mixture (in technical terms, a smaller “particle volume fraction”), the mixture was fully fluid (top image, orange background). When the ratio of particles-to-liquid was high, the mixture was granular (blue background). And in-between these ratios, whether the mixture formed clumps, or granules, depended on how it was mixed (green background). Vigorous mixing (top row) formed large granules, which consisted of a wet, jammed interior and an outer layer of dry particles (lower image).
Their observations allowed the researchers to predict what ratio of liquid and powder is needed, and how much mixing is necessary, to create a desired outcome. (Image and research credit: D. Hodgson et al.; via Physics Today)
A cross-section of a granule, showing the wet, jammed interior (left) surrounded by a region of dry particles (center, enclosed between red dashes). Dolphins Playing With Bubble Rings
Blow a jet of air underwater and you can make a bubble ring. It takes some practice for humans, or you can use a device. In this video, a team introduced wild dolphins to a bubble-ring-making machine and observed how the dolphins reacted. After some initial wariness, the animals played with them for hours, creating games and having fun. Note that there are some dolphins who create their own bubble rings to play with, so it’s hard to say that these particular dolphins have never seen a bubble ring before. But even if they have seen the bubbles, they wouldn’t have seen a machine making them. (Image and video credit: BBC Earth)
Dune Fields From Space
An astronaut captured this image of the Oyyl Dune Field in Kazakhstan from the International Space Station. To the south and east of the dune field (right and lower parts of image) there are fluvial floodplains, sources of sediment that feed the dunes. With sufficient wind and sand sources, the dune field has grown in a topographic low spot roughly 90 meters lower than the surrounding steppes. Dark specks scattered across the sands are clusters of vegetation, a sign that the dunes may get anchored rather than continue to shift in the wind. (Image credit: NASA; via NASA Earth Observatory)
Dance of the Coral Polyps
Coral reefs are made of up small organisms, called coral polyps, that live together in a colony. Individual polyps can expand, contract, and wave in the flow around them, and, in a recent study, researchers looked at whether changing conditions in temperature and light wavelength can affect polyp movement. To do so, they built a little flow control tank around a coral nubbin containing several polyps.
Under normal light and temperature conditions, they found the polyps’ motions are correlated. (Scientists don’t know why this is the case, but it could help with foraging or photosynthesis for the organisms.) When temperatures rise and light levels shift to bluer wavelengths — simulating warmer and rising oceans — the polyps lose their coordination. Without knowing the purpose behind the motion, scientists can’t yet say what that lack of coordination means, but the team believes their experimental methods can be adapted to help answer those questions, perhaps even in natural, rather than lab-created, circumstances. (Image credit: S. Ravaloniaina; research credit: S. Li et al.; via APS Physics)
“Haut”
In Susi Sie’s “Haut” the camera seems to fly over ever-shifting landscapes. In reality, these are macro images, created (I think) by dyes and patterns atop a water bath. But they look like vistas we could find on Earth or Mars — giant dune fields, calving glaciers, and river-divided canyons. For something similar in color, check out Roman De Giuli’s “Geodaehan.” (Video credit: S. Sie)
Cloud Streets
Parallel lines of cumulus clouds stream over the Labrador Sea in this satellite image. These cloud streets are formed when cold, dry winds blow across comparatively warm waters. As the air warms and moistens over the open water, it rises until it hits a temperature inversion, which forces it to roll to the side, forming parallel cylinders of rotating air. On the rising side of the cylinder, clouds form while skies remain clear where the air is sinking. The result are these long, parallel cloud bands. (Image credit: J. Stevens; via NASA Earth Observatory)