FYFD

Category: Research

  • Acoustically Trapping Nanoparticles

    Acoustically Trapping Nanoparticles

    Micrometer-sized particles can be trapped in place against a flow using acoustic waves. But smaller nano-sized particles feel less radiation pressure from acoustic waves, and so keep moving in the flow. But new work shows that it is possible to trap those nanoparticles with some additional help.

    In this case, researchers seeded their flow with microparticles that were held in place by acoustic waves against the background flow. When nanoparticles were added to the mix, they remained trapped in the wells between microparticles due to a combination of acoustic forcing and the hydrodynamic shielding of the nearby large particles. (Image credit: P. Czerwinski; research credit: A. Pavlič and T. Baasch; via APS)

    Fediverse Reactions
  • Turbulence-Suppressing Polymers

    Turbulence-Suppressing Polymers

    Adding just a little polymer to a pipe flow speeds it up by reducing drag near the wall. But the effects on turbulence away from the wall have been harder to suss out. A new experiment shows that added polymers suppress eddy formation in the flow and reduce how much energy is lost to friction and, ultimately, heat. In particular, the researchers found that polymer stress helped stabilize shear layers in the flow and prevent them from destabilizing into more turbulent flow. (Image credit: S. Wilkinson; research credit: Y. Zhang et al.; via APS)

    Fediverse Reactions
  • Ocean Bubbles Capture Carbon

    Ocean Bubbles Capture Carbon

    As humanity pumps carbon dioxide into the atmosphere, the ocean absorbs about a quarter of it. This exchange happens largely through bubbles created by breaking waves. When waves grow large enough to break, their crests curl over and crash down, trapping air beneath them. The turbulence of the upper ocean can push these buoyant bubbles meters under the surface, where the gases inside them dissolve into the surrounding water. This is how the ocean gets the oxygen used by marine animals, but it’s also how it gathers up carbon dioxide.

    Current climate models often approximate this process using only the wind speed, but a recent study took matters a step further by modeling wave breaking and bubble generation, too. While they found a global carbon uptake that was similar to existing models, the researchers found their breaking wave model showed more variability in where carbon gets stored. For example, more carbon got absorbed in the southern hemisphere, where oceans are consistently rougher, than in the northern hemisphere, where large landmasses shelter the oceans. (Image credit: J. Kernwein; research credit: P. Rustogi et al.; via Eos)

    Fediverse Reactions
  • The Start of a Supernova

    The Start of a Supernova

    Stars about eight times more massive than our sun end their lives in supernovas, incredible explosions that rip the star apart. The earliest stages of this explosion are something we’ve never observed firsthand, until now. A new study reports observations of the supernova explosion SN 2024ggi, detected here on Earth on 10 April 2024. Only 26 hours later, researchers pointed the Very Large Telescope at it, capture data that revealed its oblong shape as the initial explosion reached the star’s surface.

    What you see above and below are not the actual supernova. They are an artist’s conception of the event, based on the researchers’ observation data. That data is enough to rule out several existing supernova models and will no doubt guide new models of star death going forward. (Image credit: ESO/L. Calçada; research credit: Y. Yang et al.; via Gizmodo)

    Fediverse Reactions
  • Quantum Rayleigh-Taylor Instability

    Quantum Rayleigh-Taylor Instability

    The Rayleigh-Taylor instability–typically marked by mushroom-shaped plumes–occurs when a dense fluid accelerates into a less dense one. But researchers have now demonstrated the effect at quantum scales, too.

    For their experiment, the group used a Bose-Einstein condensate of sodium atoms and made the interface between them by exciting half of the atoms into a spin-up state and half into a spin-down one. With the interface is place, they reversed the magnetic field gradient, inducing a force on the atoms equivalent to the buoyant force seen in conventional Rayleigh-Taylor instabilities. As shown above, the interface first warped, then developed Rayleigh-Taylor mushrooms and eventually became turbulent. (Image and research credit: Y. Geng et al.; via Physics World)

    Fediverse Reactions
  • Deep Breaths Renew Lung Surfactants + A Special Announcement

    Deep Breaths Renew Lung Surfactants + A Special Announcement

    Taking a deep breath may actually help you breathe easier, according to a new study. When we inhale, air fills our alveoli–tiny balloon-like compartments within our lungs. To make alveoli easier to open, they’re coated in a surfactant chemical produced by our lungs. Just as soap’s surfactant molecules squeezing between water molecules lowers the interface’s surface tension, our lung surfactants gather at the interface and lower the surface tension, making alveoli easier to inflate.

    But things are a little more complicated in our lungs than in our kitchen sink because of our constant cycle of breathing, which stretches and compresses our lungs’ surfaces and surfactant layers. Imagine a flat interface, lined with surfactant molecules; then stretch it. As the interface stretches, gaps open between the surfactant molecules and allowing molecules from the interior of the liquid to push their way to the newly stretched interface, changing the surface tension. If the interface gets compressed, some of the excess molecules will get pushed back into the liquid bulk.

    In looking at how lung surfactants respond to these cycles of compression and stretching, the researchers found that the lung liquid develops a microstructure during cycles of shallow breathing that makes the surface tension higher, thus making lungs harder to fill. In contrast, a deep breath like a sigh replenished the saturated lipids at the interface, lowering surface tension and making lungs more compliant. So a deep sigh actually can help you breathe easier. (Image credit: F. Møller; research credit: M.. Novaes-Silva et al.; via Gizmodo)

    P.S. — I’ve got a book (chapter)! Several years ago, I joined an amazing group of women to write two books (one for middle grades and one for older audiences) about our journeys as scientists. And they are out now! In fact, today we’re holding a “Book Bomb” where we aim for as many of us as possible to buy the book(s) on the same day. If you’d like to join (and get ahead on your gift shopping), here are (affiliate) links:

    Fediverse Reactions
  • Wobbling Plasma Could Help Planets Grow

    Wobbling Plasma Could Help Planets Grow

    To form planets, the dust and gas around a star has to start clumping up. While there are many theories as to how this could happen, it’s a difficult process to observe. A recent study shows that a magnetorotational (MR) instability could do the job.

    The team used a Taylor-Couette set-up (where an inner cylinder rotates inside an outer cylinder) filled with a liquid metal alloy. With the cylinders moving relative to one another at over 2,000 rotations per minute, the team measured how the magnetic field changed in the churning fluid. Parts of the liquid metal formed free shear layers, and within these, the MR instability occurred, causing some regions to slow down and others to speed up.

    The experiments suggest that triggering a MR instability is easier to achieve than once thought, which supports the possibility that it occurs in protoplanetary disks, helping to drive dust together into planets. (Image credit: ALMA/ESO/NAOJ/NRAO; research credit: Y. Wang et al.; via Eos)

    Fediverse Reactions
  • Wave Energy Through the Meniscus

    Wave Energy Through the Meniscus

    Even small changes to a meniscus can change how much wave energy passes through it. A new study systemically tests how meniscus size and shape affects the transmission of incoming waves.

    As seen above, the meniscus was formed on a suspended barrier. By changing the barrier size and wettability as well as the characteristics of incoming waves, researchers were able to map out how the meniscus affected waves that made it past the barrier.

    Oblique view of meniscus experiment showing incoming waves (moving from right to left) passing through a barrier and meniscus. Upper view shows 15Hz waves; lower one shows 5 Hz waves.

    In particular, they found that drawing the meniscus upward by raising the barrier would, at first, enhance wave transmission but then suppressed wave energy as the barrier moved higher. They attributed the change in behavior to an interplay between water column height and meniscus inclination. (Research and image credit: Z. Wang et al.; via Physics World)

    Fediverse Reactions
  • Why Sharper Knives Mean Fewer Onion Tears

    Why Sharper Knives Mean Fewer Onion Tears

    Onions are a well-known source of tears for many a cook. And while the chemical source of their power–onions release a chemical that reacts in our eyes to produce tears–has been known for years, no one has looked at the fluid dynamics in the process until now.

    Video of droplets sprayed as a knife cuts into an onion.

    As seen above, a knife piercing the onion’s surface releases a mist of high-speed droplets, followed by a slower spray. Much like a citrus fruit’s microsprays, the onion’s fountain depends on both solid and fluid mechanics. As the knife presses into the onion’s stiffer outer layer, pressure builds in the softer layer underneath, which contains pores of fluid. Once the knife breaks the epidermis, that pressurized fluid sprays out.

    The good news is that the team also confirmed a common culinary wisdom: using a sharper knife and a slower, gentler cut will reduce the spray and its speed, resulting in fewer tears. (Image credit: M. Stone; research credit: Z. Wu et al.)

    Fediverse Reactions
  • Oceans Could “Burp” Out Absorbed Heat

    Oceans Could “Burp” Out Absorbed Heat

    Earth’s atmosphere and oceans form a complicated and interconnected system. Water, carbon, nutrients, and heat move back and forth between them. As humanity pumps more carbon and heat into the atmosphere, the oceans–and particularly the Southern Ocean–have been absorbing both. A new study looks ahead at what the long-term consequences of that could be.

    The team modeled a scenario where, after decades of carbon emissions, the world instead sees a net decrease in carbon–which could be achieved by combining green energy production with carbon uptake technologies. They found that, after centuries of carbon reduction and gradual cooling, the Southern Ocean could release some of its pent-up heat in a “burp” that would raise global temperatures by tenths of a degree for decades to a century. The burp would not raise carbon levels, though.

    The research suggests that we should continue working to understand the complex balance between the atmosphere and oceans–and how our changes will affect that balance not only now but in the future. (Image credit: J. Owens; research credit: I. Frenger et al.; via Eos)

    Fediverse Reactions