Physics

Order from chaos: Vortex studies are first proof of decades-old theory

Two Australian studies published this week offer the first proof of a 70-year-old theory of turbulence. Turbulence, with its seemingly random and chaotic motion of the fluid, is a notoriously difficult problem, for which there is no general theoretical description. (In fact, the Clay Mathematics Institute offers a million dollar prize to anyone that comes up with a theory of turbulence.)

Researchers observe 70-year-old prediction, with wide-reaching effects

As you stir milk into a cup of coffee, you will see fluid turbulence in action -- rapid mixing that has defied deep scientific understanding. Researchers set out to learn more about the everyday enigma of turbulence by using the remarkable properties of superfluids, strange quantum fluids able to flow endlessly without any friction.

Order from chaos: Australian vortex studies are first proof of 70-year-old theory of turbulence in fluids

Two Australian studies published this week offer the first proof of a 70-year-old theory of turbulence.

A peculiar ground-state phase for superconductor NbSe2 -- It's a Bose metal!

The application of large enough magnetic fields results in the disruption of superconducting states in materials even at drastically low temperature, thereby changing them directly into insulators -- or so was traditionally thought. Now, scientists report curious multi-state transitions of these superconductors: going from superconductor to special metal and then to insulator.

Applying pressure is way toward generating more electricity from waste heat

The ability of a thermoelectric material to produce electricity from waste heat was improved more than twofold. The researchers applied pressure to the material to induce a Lifshitz phase transition and, in a world-first, found a direct link between the Lifshitz transition and changes in the material's thermoelectric properties. Understanding the effect of the Lifshitz transition on quantum phenomena could lead to improved thermoelectric materials.

The often-heard complaint that motorcycles can influence the outcome of races is justified

In professional cycling, in-race motorcycles such as TV motorcycles drive in between the riders. In the slipstream behind the motorcycle, cyclists can gain time. For the first time, the exact extent of this advantage has been scientifically investigated. It turns out to be even more advantageous than expected. Using computer simulations and wind tunnel measurements, Professor Bert Blocken of Eindhoven University of Technology and KU Leuven—in collaboration with software company ANSYS—investigated the effect.

A new quasi-2D superconductor that bridges a ferroelectric and an insulator

Researchers at the Zavoisky Physical-Technical Institute and the Southern Scientific Center of RAS, in Russia, have recently fabricated quasi-2-D superconductors at the interface between a ferroelectric Ba0.8Sr0.2TiO3 film and an insulating parent compound of La2CuO4. Their study, presented in a paper published in Physical Review Letters, is the first to achieve superconductivity in a heterostructure consisting of a ferroelectric and an insulator.

Generating more electricity from waste heat by applying pressure

Researchers at Osaka University have been able to enhance the power factor of a promising thermoelectric material by more than 100% by varying the pressure, paving the way for new materials with improved thermoelectric properties. Thermoelectric materials have the unique ability to generate electricity from temperature differences and therefore could potentially be used to convert otherwise wasted heat (such as heat from hot laptops or servers) into usable electricity.

Experiment reverses the direction of heat flow

Heat flows from hot to cold objects. When a hot and a cold body are in thermal contact, they exchange heat energy until they reach thermal equilibrium, with the hot body cooling down and the cold body warming up. This is a natural phenomenon we experience all the time. It is explained by the second law of thermodynamics, which states that the total entropy of an isolated system always tends to increase over time until it reaches a maximum. Entropy is a quantitative measure of the disorder in a system.

Proposed set of conservation laws find order in the chaos of turbulence

Turbulence can be found in places large and small, from exploding supernovae and sprawling ocean currents, to the unstable plasmas that form within tiny fusion fuel cells bombarded with lasers.

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