#viscosity — Public Fediverse posts

@telescoper
I played with #superfluids back in my 20th Century youth, so I’ll give this a go.

Curiously, a “dry” fluid with no #viscosity can be great at making things wet! I speak of course of #superfluid #helium-4, renowned for escaping any open container, flowing as a film a few atoms thick and climbing walls with forces much stronger than puny gravity can resist.
Apply this concept to an #armpit and the consequences are clear: no pore unclogged, no bacterium unstifled.

Quantum Dry

I was taken aback by the description “QUANTUM DRY” but then I remembered the Chapter 40 of the Feynman Lectures on Physics on the topic of The Flow of Dry Water, by which is meant the flow of a fluid with zero viscosity (i.e. inviscid flow). I therefore infer that the material of which this product is composed is a quantum superfluid, i.e. a quantum fluid with zero viscosity. Can someone point me to the scientific literature on superfluid anti-perspirants?

Is honey a good candidate for the Leidenfrost effect?

LeidenForce quiz of the day: can you solve our Fake or Fact?

In our Fake or Fact series, we test your science knowledge about the Leidenfrost effect!

Surprised by the result? 👇

#LeidenfrostEffect #ScienceFact #Honey #Bubbles #Viscosity #FakeOrFact

🎨🧩 Ah, "Fluid Simulation for Dummies"—because clearly the world needed another convoluted guide to answer the burning question: "How can I make water look like Jell-O in my app?" 🍮🤦‍♂️ The author generously sprinkles in some unrelated aviation content, just in case you needed a break from the riveting world of simulated #viscosity. 🛩️💧
https://www.mikeash.com/pyblog/fluid-simulation-for-dummies.html #FluidSimulation #ForDummies #AppDevelopment #Jello #WaterAnimation #HackerNews #ngated

Plucking Droplets

A sudden breeze can pluck droplets hanging from a stem. Here, researchers recreate that phenomenon in the laboratory. With a close-up view and high-speed images, we can enjoy every detail of the detachment and break-up. As the wire pulls away, it drags a liquid sheet off the droplet. The thicker rims on either side of the sheet eventually collide, creating a jet that stretches, deforms, and, at last, breaks. (Video and image credit: D. Maity et al.)

Competing Time Scales

Fluid dynamics often comes down to a competition between the different forces acting in a flow. Inertia, surface tension, viscosity, gravity, rotation — flows can be affected by all of these and more. In this video, researchers describe the three dominant forces in a rotating fluid like a planet’s atmosphere: viscosity, the fluid’s resistance to flowing; inertia, the fluid’s resistance to accelerating; and rotation, the overall spin of a fluid.

As shown in the video, which of these three forces dominates will change depending on the speed at which the force acts. We quantify this concept using time scales; the force with the smallest time scale can act fastest and will, therefore, win the tug-of-war. (Video and image credit: UCLA SpinLab)

#DIYFluids #flowVisualization #fluidDynamics #inertia #mathematics #physics #rotatingFlow #science #viscosity

Venusian Gravity Currents

Radar measurements of Venus‘s surface reveal the remains of many volcanic eruptions. One type of feature, known as a pancake dome, has a very flat top and steep sides; one dome, Narina Tholus, is over 140 kilometers wide. Since their discovery, scientists have been puzzling out how such domes could form. A recent study suggests that the Venusian surface’s elasticity plays a role.

According to current models, the pancake domes are gravity currents (like a cold draft under your door, an avalanche, or the Boston Molasses Flood), albeit ones so viscous that they may require hundreds of thousands of Earth-years to settle. Researchers found that their simulated pancake domes best matched measurements from Venus when the lava was about 2.5 times denser than water and flowed over a flexible crust.

We might have more data to support (or refute) the study’s conclusions soon, but only if NASA’s VERITAS mission to Venus is not cancelled. (Image credit: NASA; research credit: M. Borelli et al.; via Gizmodo)

#fluidDynamics #gravityCurrents #physics #planetaryScience #science #venus #viscosity #viscousFlow #volcano

Room-Temperature Zwitterionic Liquids You Can Actually Stir:
Incorporation of a flexible oligoether chain into the spacer between cationic and anionic units reduces viscosity effectively
https://www.chemistryviews.org/room-temperature-zwitterionic-liquids-you-can-actually-stir/

#zwitterionicliquids #viscosity #chemistry #chemistryviews #chemviews

I'll take the opportunity to open a small parenthesis on what #rheology aka “the science of the flow”, is: the term, which can be used both for fluids and (some classes of) deformable solids describes the relationship between stress and strain in a continumm.

To wit, for something to flow (or deform), there must be a force applied. The relation between this force and how much (and how quickly) the continuum deforms is what rheology is about.

Rheology deals with two main classes of behavior: #plasticity and #viscosity.

Plastic behavior refers to (permanent) deformations whose magnitude depends on the applied force: smaller forces result in smaller deformations, larger forces in larger deformations. This is typical of solids.

Viscous behavior refers to deformations whose rate depends on the applied force: in this sense deformations can be “infinite” (the distance between two given points can grow arbitrarily), and as long as the force is applied the deformation will grow. #Viscosity determines how strongly the continuum (typically a fluid) resits to the deformation, and thus how quickly (or slowly) it deforms.

And of course you can have hybrid behaviors (viscoplastic, viscoelastic, viscoplastoelastic).

5/

A New Mantle Viscosity Shift

The rough picture of Earth’s interior — a crust, mantle, and core — is well-known, but the details of its inner structure are more difficult to pin down. A recent study analyzed seismic wave data with a machine learning algorithm to identify regions of the mantle where waves slowed down. These shifts in seismic wave speed occur in areas where the mantle’s viscosity changes; a higher viscosity makes waves travel slower.

The team found seismic wave speed shifts at depths of 400 and 650 kilometers, corresponding to known viscosity changes. But they found shifts at 1050 and 1500 kilometers, as well — the first time anyone has shown a global viscosity shift at those depths. Their analysis suggests a higher viscosity in this mid-mantle transition zone, which could affect how tectonic plates, which rely on these slow mantle flows, move. (Image credit: NASA; research credit: K. O’Farrell and Y. Wang; via Eos)

#fluidDynamics #geophysics #mantleConvection #physics #planetaryScience #science #viscosity

Thomas Strassner and Stefan Fritsch @tudresden present a new class of tunable aryl alkyl ionic liquids (TAAILs) ➡️ https://www.beilstein-journals.org/bjoc/articles/20/110?M=y

#conductivity #IonicLiquids #viscosity
#DiamondOpenAccess 💎🔓 #BJOC

If you sandwich a viscous fluid between two plates and inject a less viscous fluid, you’ll get viscous fingers that spread and split as they grow. This research poster depicts that situation with a slight twist: the viscous fluid (transparent in the image) is shear-thinning. That means its viscosity drops when it’s deformed. In this situation, the fingers formed by the injected (blue) fluid start out the way we’d expect: splitting as they grow (inner portion of the composite image). But then, the tip-splitting stops and the fingers instead elongate into spikes (middle ring). Eventually, as the outer fluid’s viscosity drops further, the fingers round out and spread without splitting (outer arc of the image). (Image credit: E. Dakov et al.; via GoSM)

https://fyfluiddynamics.com/2024/04/evolving-fingers/

#2024gosmp #flowVisualization #fluidDynamics #HeleShawCell #instability #nonNewtonianFluids #physics #SaffmanTaylorInstability #science #shearThinning #surfaceTension #viscosity #viscousFingering

'Large data limit of the MBO scheme for data clustering: convergence of the dynamics', by Tim Laux, Jona Lelmi.

http://jmlr.org/papers/v24/22-1089.html

#viscosity #clustering #curvature

"Water flows faster and easier than honey. Similarly, our teams will go as fast as they are capable of. The real issue is finding what is slowing them down."

https://ryber.github.io/blog/2016/08/22/viscosity-vs-velocity/ #agile #velocity #vs #viscosity #software #productivity

What is the scientific word for a Fluid or semi-Fluid that holds its bead when put on a surface. Think ketchup. You could write with it, and the ketchup would mostly hold its location and height.

Is this viscosity also? Or is there a word for the vertical strength of a liquid/gel

#hydrodynamics #science #engineering #liquid #gel #viscous #viscosity

A method for #theoretically high-precision determination of the #viscosity of liquid metals using a trained artificial #neural #network. The method was successfully tested in the process of building the deep learning potential of the neural network on the example of liquid #gallium.
#AI #ArtificialIntelligence #Science #sflorg
https://www.sflorg.com/2022/12/scn12092201.html