How do we model fluids that behave partly like solids?

A physics-based Maxwell model with variable parameters improves the description of viscoelastic flows where material properties change during deformation.

🔗 https://pubs.aip.org/aip/pof/article/38/2/022012/3380412/Physics-based-Maxwell-model-with-variable

#Viscoelasticity #FluidDynamics #Rheology #PhysicsOfFluids #Modeling

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)

#dissipation #elasticTurbulence #fluidDynamics #instability #physics #polymerEffects #science #turbulence #viscoelasticity

Watch Hagfish Slime Unfurl

The eel-like hagfish has one of the best defenses in the ocean. When threatened, it releases a slime that clogs the gills of its predator but allows the hagfish itself to slough off the slime and escape. The hagfish slime’s secret weapon is long protein threads, which are initially rolled into bundles called skeins. Seen above, these skeins resemble the yarn skeins knitters and crocheters buy, but a hagfish’s skeins are only as big as the width of a human hair.

When water flows by quickly enough, the thread in a skein begins to unwind and stretch out. With enough threads unwound, the slime gets stretchy and viscous. Researchers found that it takes relatively little flow to begin this unwinding because the adhesion between threads and the surrounding fluid is higher than the thread-to-thread sticking power. (Research and image credit: M. Hossain et al., video)

#biology #fluidDynamics #hagfish #physics #rheology #science #viscoelasticity

Tides Widen Ice Cracks

When icebergs calve off of Arctic and Antarctic coastlines, it affects glacial flows upstream as well as local mixing between fresh- and seawater. A recent study points to ocean tides as a major factor in widening the ice cracks that lead to calving. The team built a simplified mathematical model of an ice shelf, taking into account the ice’s viscoelasticity, local tides, and winds. Then they compared the model’s predictions with satellite, GPS, and radar data of Antarctica’s Brunt Ice Shelf, where an iceberg the size of Greater London broke off in 2023.

Between their model and the observation data, the team was able to show that the crack that preceded calving consistently grew during the spring tides, when tidal forces were at their strongest. The work gives us one more clue for refining our predictions of when major calving events are likely. (Image and research credit: O. Marsh et al.; via Gizmodo)

#calving #fluidDynamics #iceShelf #iceberg #oceanTides #physics #science #viscoelasticity

“Droplet on a Plucked Wire”

What happens to a droplet hanging on a wire when the wire gets plucked? That’s the fundamental question behind this video, which shows the effects of wire speed, viscosity, and viscoelasticity on a drop’s detachment. With lovely high-speed video and close-up views, you get to appreciate even subtle differences between each drop. Capillary waves, viscoelastic waves, and Plateau-Rayleigh instabilities abound! (Video and image credit: D. Maity et al.)

#2024gofm #droplets #fluidDynamics #physics #science #viscoelasticity #viscousFlow

An ultrasoft viscoelastic fluid drips in this research poster from the Gallery of Soft Matter. Complex materials like this one have stretchy, elastic behaviors typical of a solid along with the flowing, viscous properties of a fluid. Here, gravity overcomes the material’s elasticity, leaving it to sag and flow. As that happens, the fluid must slide past air, and the density difference between the two fluids creates the small distortions seen on the liquid sheet. This is an example of a Rayleigh-Taylor instability. (Image credit: J. Hwang et al.)

https://fyfluiddynamics.com/2024/06/dripping-viscoelastics/

#2024gosmp #flowVisualization #fluidDynamics #instability #physics #RayleighTaylorInstability #science #viscoelasticity

Honeybees, with their stingers, get lots of attention, but the Americas have plenty of stinger-less honeymakers, too. These stingless bees are native to Mexico, where beekeepers cultivate them for pollination. Without stingers and venom, the bees use their building prowess to keep out unwanted visitors. Much of the hive — from the entrance’s nightly gate to the pods where young are stored — is built from cerumen, a substance the bees create by mixing wax with resins they collect from nearby trees. Just as they do with pollen, worker bees collect drops of resin and store them on their hind legs before flying back to the hive. The viscous fluid sticks well, until a swipe of a leg shears it enough to lower its viscosity and slide it off. (Video and image credit: Deep Look)

https://fyfluiddynamics.com/2024/06/building-in-a-stingless-hive/

#bees #biology #fluidDynamics #physics #science #shearThinning #viscoelasticity

Ballpoint pen ink is a non-Newtonian, viscoelastic fluid - formulated to have a fluid's viscosity and a gel's elasticity.

#science #sciencefacts #ballpointpen #viscoelastic #viscoelasticity #ink #nonnewtonian

Research team reveals hidden particle #interactions at the #cell surface.

#membrane #viscoelasticity #pericellular_matrix

https://phys.org/news/2023-07-team-reveals-hidden-particle-interactions.html

Just Published!

"Sounding a New Era in Biomechanics with Acoustic Force Spectroscopy"

https://link.springer.com/chapter/10.1007/5584_2022_757

#Mechanobiology #Microfluidics #Viscoelasticity #Biophysics #CellBiology