non newtonian fluid

Water confined between two cylinders flows in smooth layers when the inner one rotates. But once the speed crosses a certain threshold, the layers crumple into toroidal rolls, like a stack of bagels. Physicists call these Taylor vortices: the flow loses stability and a regular pattern emerges.

In the depths of sub-Neptunes, the most common type of planet in the Galaxy, though not one you could stand on, silicate magma and hydrogen mix into a single supercritical cocktail. Previously, it was thought that beneath the dense hydrogen atmosphere lay a sharp boundary with molten silicate, like oil on water.

A layered cake where each tier conducts electricity differently: that's the structure of the crystal La3Ni2O7, a compound of nickel, lanthanum, and oxygen. Current flows differently along the layers than across them.

A solid under a microscope is not a monolith at all. In glass, polymer, or solidified resin, atoms are arranged randomly, and as a result, the material's properties vary from point to point. On large scales, we are used to describing them with smooth fields, like temperature or pressure in a room. But when you zoom down to a few atomic layers, that smoothness disappears.

The brain self-cleans its waste: cerebrospinal fluid flows through narrow channels surrounding arteries. The channel walls are soft and ripple with each pulse, and the tissue is porous like a sponge. Every heartbeat turns arteries into tiny pumps, driving fluid through the pores.

Inside planets and stars, in rotating oceans of plasma, turbulent flows, Coriolis forces, and magnetic tension collide. The central question is how the energy of this chaos crystallizes into a stable magnetic framework that can last billions of years.

When physicists drive electrons through an ultrapure gallium arsenide channel at helium temperatures, they expect to see a well-behaved, almost ideal fluid.

A stone falls into a pond, and ripples spread evenly in all directions. But some media behave as if the wave knows which way to turn, like water that only swirls clockwise. This asymmetry comes from odd viscosity and odd elasticity — properties of media with broken mirror symmetry.

Magnetic particles are attached to the surface of the diamond by DNA strands, like puppets on strings. They constantly dance under the thermal motion of the liquid molecules. The liquid's viscosity sets the pace: in honey, the particles barely tremble; in alcohol, they dance quickly.

When you squeeze ketchup out of a bottle, you're battling its stubbornness: it sits still at first, then suddenly shoots out in a blob. That's typical non-Newtonian behavior — resistance to flow changes with how hard you push. But the authors of a new study found a way to almost completely eliminate that resistance.

Strike a bell, and it hums at a single pitch. But if you place a second clapper inside, and they ring without touching each other, the sound becomes more complex. That's roughly how the neutron star from the new study is built. It's not just a hot sphere: inside, two immiscible fluids can flow — for instance, superfluid neutrons and ordinary plasma.

A tiny oil drop squeezes through a water channel narrower than itself. In pure water, it crawls along calmly, like a round bead. But add a little soap to the water, and the drop begins to bend, like a caterpillar.

The void can produce particles if a strong enough field is applied. Physicists call this the Dirac–Klein paradox. Previously, explaining it required the most complex calculations of quantum field theory. But we can make do with a visual image: a tightly stretched rubber band with a knot. The knot is a particle.

In a narrow gap between two plates, water from humid air collects on its own: this is capillary condensation. If the gap is only a few nanometers wide, water no longer behaves like a continuous liquid: every molecule counts.

The boundary between two liquids is like an invisible skin: it's there, but you can't touch it with your finger. Scientists have found a way to measure its elasticity without touching it. They made a tiny probe oscillate above the surface, and between the probe and the interface lay a thin film of liquid.

Water deep within the Earth is compressed more than a thousandfold compared to the surface. Even there, it continues to flow, but its internal structure changes. Researchers measured how water resists flow and compression as pressure rises from zero to 1.6 gigapascals — equivalent to placing a 16-ton weight on every square centimeter.

In a protoplanetary disk, a cloud of gas and dust around a young star, dust grains don't just fly in circles. They are carried by the gas flow, like sand by the wind, and in turn alter that flow. Layers emerge, sliding past each other, and at their boundaries an instability arises — waves and vortices.

In ordinary water, ripples from a thrown stone spread in even concentric circles. But imagine a liquid whose molecules are like tiny screws with a right-handed thread. In such a medium, the surface acts like a one-way street: waves can only travel in a certain direction.

Turning light gases like hydrogen and nitrogen into metal is a long-standing dream of physicists. In a new experiment, nitrogen was compressed to 130–140 gigapascals (pressure equivalent to 14 million kilograms pressing on a fingernail) and heated to 3000°C.

Metal is like a rope made of many strands: pull too hard and it snaps. Engineers have long sought a way to make it both strong and flexible at the same time. Typically, additives that increase strength make the metal brittle. But a team of materials scientists found a loophole: they added a small amount of nitrogen to the CrMnFeCoNi alloy, just one atom in a hundred, and got an unexpected result.

A thin plate stands across a flow of water or air. Behind it, a wake forms — a region where the flow becomes tangled and mixed. Usually, such a wake becomes turbulent when the flow speed is high enough, quantified by the Reynolds number.

If you dump a handful of coins on a table, the surface becomes bumpy. But add more coins, and they spread out into a flat layer on their own. Something similar happens when you deposit ultra-thin films of individual molecules onto a substrate. At first, islands appear on the surface — molecules cluster together like people in a queue. The film gets rougher and rougher.

A drop of a thick cornstarch-water mixture falls onto a table. Normally, such a mixture solidifies instantly upon a sharp impact: you can even run across a pool filled with it. But in this experiment, things went differently. The high-speed camera captured that in the first instant after contact, the drop spreads out like an ordinary liquid.

Empty space is never truly still. It teems with tiny energy fluctuations, like a sculptor's raw clay. In a new experiment, a thin film of superconducting material was placed inside a cavity designed to trap terahertz light, a form of invisible radiation. The cavity acted as a mold, shaping the vacuum fluctuations around the film.

Helium on graphite behaves like an acrobat who simultaneously slides along a tightrope and holds a pose.