FYFD

Category: Research

  • Brown Dwarfs and Their Stripes

    Brown Dwarfs and Their Stripes

    Brown dwarfs are neither stars nor gas giants but something in between. Our two nearest brown dwarf neighbors are roughly equivalent to Jupiter in size but about 30 times more massive. Since these objects are so dim, little is known about their structure. Do they resemble stars in their atmospheric patterns or gas giants like Jupiter?

    To find out, a team of researchers studied two nearby brown dwarfs with the Transiting Exoplanet Survey Satellite. They were able to map the objects’ varying lightcurves and model an upper atmosphere consistent with those observations. They found that both dwarfs have high-speed winds running parallel to their equators, meaning that they likely have stripes like Jupiter. The similarities even extended to the brown dwarfs’ poles, where — like on Jupiter — the atmosphere became dominated by local vortices. (Image credit: NASA/JPL; video credit: Steward Observatory; research credit: D. Apai et al.; via Gizmodo)

  • How Wombats Make Stackable Feces

    How Wombats Make Stackable Feces

    Wombats are unique among the animal kingdom for their ability to produce cubic feces approximately the size and shape of dice. Researchers found that wombats accomplish this geometric feat thanks to the structure of their intestines, which have bands of differing stiffness that run the full length of their guts. When the intestines contract, the stiffer bands contract first, gradually shaping and sculpting the corners of the feces.

    The results have implications both for manufacturing soft materials and for human health. One of the early effects of colon cancer is a stiffening of portions of the intestine; that means that doctors may be able to use changes in the shape of a patient’s feces as a warning sign for diagnosis. (Image and research credit: P. Yang et al.; video credit: Royal Society of Chemistry; via Gizmodo)

  • Microfluidic Pac-Man

    Microfluidic Pac-Man

    Researchers are using coalescence to guide microdroplets through a miniature maze, a la Pac-Man. To steer the main droplet, they place a smaller droplet nearby in the direction they want to move. When the drops coalesce, it moves the main droplet in the target direction. By repeating the process, researchers can drive the drop through a maze or perform tasks like cleaning or transporting particles by picking them up. Learn more over at APS Physics. (Image and research credit: J. Chaaban et al.; via APS Physics)

  • This Is Your Brain

    This Is Your Brain

    The human brain, like an egg, consists of soft matter bathed in a fluid and encased in a hard shell. To better understand how our brains respond to sudden accelerations, researchers looked at how egg yolks behave. In a purely translational impact (Image 1), the egg yolk deforms very little. But rotational motions (Images 2 and 3) cause major effects because of the imbalance between pressure forces outside the yolk’s membrane and the centrifugal forces within it. Rotational deceleration was particularly potent (Image 3).

    The researchers’ findings are consistent with concussion research, which has shown that impacts with rotational acceleration/deceleration inside the skull are the most damaging. Based on the yolk’s deformation, such impacts likely stretch neurons and disturb their delicate network. (Image credit: cracked egg – K. Nielsen, others – J. Lang et al.; research credit: J. Lang et al.; via Physics World; submitted by Kam-Yung Soh)

  • Featured Video Play Icon

    Viscoplastic Drop Impact

    There are many materials that don’t behave exactly as a fluid or a solid, instead displaying characteristics of both. In this video, we see drops of hair gel falling into water. The gel is viscoplastic – showing some of the viscous behavior of a fluid and some of the plastic behavior (the inability to change back to its initial shape) of a solid.

    On impact, the gel deforms due to the forces on it, but the final shape does not depend solely on the amount of force; instead, it’s the rate at which the forces are applied that determines the final shape. By tuning the impact speed and the gel stiffness, it’s possible to make many final capsule shapes, something that could be useful in applications like drug manufacturing. (Image and video credit: M. Jalaal et al.)

  • Flexible Wings Aid Butterfly Flight

    Flexible Wings Aid Butterfly Flight

    Butterflies are some of the oddest flyers of the insect world, given the large size of their wings relative to their bodies. That could be a recipe for inefficient flight, but a new study shows that butterflies’ large flexible wings actually help them take off quickly.

    When lifting their wings, butterflies use an unusual clapping motion, with the leading edges of their wings coming together before the rest of the wings. This motion helps cup and direct air, creating most of the butterfly’s thrust, according to the researchers. The wings’ flexibility is key to this. Using artificial wings — both stiff and flexible — researchers found that the flexible wings generated 22% more useful impulse and were 28% more efficient. For a tiny flyer with frequent take-offs, that’s an enormous savings! (Image, video, and research credit: L. Johansson and P. Henningsson; via BBC; submitted by Kam-Yung Soh)

  • Inside Drying Wood

    Inside Drying Wood

    Wood must dry before it can be used in most applications, but with its complex internal structure exactly how wood dries out has been unclear. New experiments combining MRI and x-ray imaging reveal a process quite different than expected.

    Inside hardwoods like poplar — the species studied here — wood contains both solid structures and pores where water can gather. The pores do not form a fully interconnected network, so capillary action alone is unable to carry water through the pores and out to a surface where it can evaporate.

    Instead, researchers found that water evaporating at the surface came from so-called “bound water” in the wood’s solid structures. As the bound water evaporated, it caused water in the wood pores to diffuse into the solid walls, becoming bound and continuing to feed the evaporation. (Image and research credit: H. Penvern et al.; via APS Physics)

  • Cutting Coronavirus Risk in Cars

    Cutting Coronavirus Risk in Cars

    Even in a pandemic, it’s sometimes necessary to share a car with someone outside one’s bubble. When that’s the case, it’s important to know how to limit risks of coronavirus exposure. For this study, researchers used computational fluid dynamics to simulate flow around and inside a Prius-like four-door sedan with a driver and a single passenger located in the rear passenger-side seat. Assuming the air conditioner was on and the car was moving at 50 miles per hour, the researchers found that the baseline flow of air inside the car moves from the back of the cabin toward the front. With the windows closed, the simulation suggested that 8-10% of the aerosol particles exhaled by one passenger could reach the other.

    Opening the car’s windows increases the ventilation and reduces exposure risk. The best configuration the researchers found opened two windows: the front passenger-side window and the rear driver-side window. By opening the window opposite each person, the airflow in the car creates a sort of curtain between the two that reduces aerosol exposure to only 0.2-2% of what’s exhaled by the other occupant. (Image credit: rideshare – V. Xok, CFD – V. Mathai et al.; research credit: V. Mathai et al.; via NYTimes; submitted by Kam-Yung Soh)

    Computed streamlines for flow through a sedan with a driver and one rear passenger, with each opposite window opened.
  • Bubbles Affect Lava Flow

    Bubbles Affect Lava Flow

    During the 2018 eruption at Kilauea, scientists noticed that the lava flowed very differently depending on how bubbly it was. In this experiment, researchers used corn syrup as a lava analogue and studied how bubbly and particle-filled bubbly flows differed from bubble-free ones. They found that bubble-free syrup flowed fastest, while particle-filled bubbly flows were by far the slowest.

    The bubbles also affected the structure of the flows. Large bubbles gathered near the surface of the flow’s leading edge, allowing faster flow beneath. And in the particle-filled flow, the corn syrup developed channels that flowed at different speeds. The authors hope that their relatively simple experimental set-up will inspire more research on bubbly lava flows. (Image and research credit: A. Namiki et al.; via AGU Eos; submitted by Kam-Yung Soh)

  • Sand Traps

    Sand Traps

    Antlion larvae catch prey by digging conical pits in sand. The steep walls of the trap are near the angle of repose, the largest angle a granular material can maintain before grains slide down. When a hapless ant wanders into the trap, the antlion throws sand from the center of the pit, triggering a sandslide that carries the ant downward. The act of flinging sand also helps the antlion maintain the pit, correcting any disruptions to the pit’s steep sides caused by its flailing prey. (Image and research credit: S. Büsse et al.; via Science)