News & Views |
Featured
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Article |
Floating under a levitating liquid
Manipulation of the effective gravity of an oscillating liquid creates stable buoyancy in the lower surface of a liquid layer levitating above air, allowing bodies to float upside down.
- Benjamin Apffel
- , Filip Novkoski
- & Emmanuel Fort
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Article |
Liquid flow and control without solid walls
Wall-free liquid channels surrounded by an immiscible magnetic liquid can be used to create liquid circuitry or to transport human blood without damaging the blood cells by moving permanent magnets.
- Peter Dunne
- , Takuji Adachi
- & Thomas M. Hermans
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Research Highlight |
Why a glass of wine cries
Shock waves might explain the flow of wine droplets after a glass is swirled.
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Article |
Loopy Lévy flights enhance tracer diffusion in active suspensions
A theoretical framework describing the hydrodynamic interactions between a passive particle and an active medium in out-of-equilibrium systems predicts long-range Lévy flights for the diffusing particle driven by the density of the active component.
- Kiyoshi Kanazawa
- , Tomohiko G. Sano
- & Adrian Baule
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Nature Video |
Birds gliding through bubbles reveal aerodynamic trick
Gliding birds use tail to generate extra lift and reduce drag.
- Shamini Bundell
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Article |
A droplet-based electricity generator with high instantaneous power density
A device involving a polytetrafluoroethylene film, an indium tin oxide substrate and an aluminium electrode allows improved electricity generation from water droplets, which bridge the previously disconnected circuit components.
- Wanghuai Xu
- , Huanxi Zheng
- & Zuankai Wang
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News & Views |
The physics of ice skating
The slipperiness of ice is poorly understood at a microscopic level. Experiments that probe how the surface of ice melts and flows in response to wear help to explain the exceptionally low friction that underpins winter sports.
- Daniel Bonn
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Research Highlight |
Bourbon or Scotch? A droplet’s dynamics reveal the truth
A whisky’s country of origin can be gleaned from the residue of an evaporated droplet.
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Article |
Braess’s paradox and programmable behaviour in microfluidic networks
Microfluidic systems controlled by a single driving pressure are programmed to exhibit complex flow-switching schemes and a fluid analogue of Braess’s paradox by exploiting fluid inertia and network design.
- Daniel J. Case
- , Yifan Liu
- & Adilson E. Motter
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News & Views |
Micro-engineered liquid flow dissolves solids without dispersing them
Microfluidic devices have revolutionized biological assays, but complex set-ups are required to prevent the unwanted mixing of reagents in the liquid samples being analysed. A simpler solution has just been found.
- Robert Hołyst
- & Piotr Garstecki
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News & Views |
Droplet motion electrically controlled
The movement of small droplets on a substrate is governed by surface-tension forces. A technique that can tune the surface tension of robust oxide substrates for droplet manipulation could open up many applications.
- Frieder Mugele
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Books & Arts |
Leonardo da Vinci’s laboratory: studies in flow
On the 500th anniversary of the Renaissance icon’s death, Martin Kemp looks anew at his innovative experimental models for the motion of water and blood.
- Martin Kemp
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Letter |
Turbulent convective length scale in planetary cores
Numerical modelling of rotating turbulent convective flows shows that the length scale of convection in planetary cores is set by the flow speed and not by the fluid viscosity.
- Céline Guervilly
- , Philippe Cardin
- & Nathanaël Schaeffer
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Research Highlight |
Physicists tackle a delicate challenge: making the ideal crêpe
Computer simulations validate common technique for creating an even pancake.
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Books & Arts |
From counting with stones to artificial intelligence: the story of calculus
Anil Ananthaswamy savours a history of the mathematics used to track changes in everything from DNA to machine learning.
- Anil Ananthaswamy
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Letter |
Molecular streaming and its voltage control in ångström-scale channels
Pressure-driven transport of aqueous salts through ångström-scale channels created from two-dimensional materials shows a transistor-like effect in which applying a tiny bias voltage can increase transport by up to 20 times.
- T. Mouterde
- , A. Keerthi
- & B. Radha
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Research Highlight |
Micro-droplets in minuscule channels need no help to get ahead
Channel design allows fluid droplets to self-propel in a controlled manner.
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Research Highlight |
How lagging swimmers can use physics to get ahead
Racers can take advantage of a competitor ahead of them to save energy.
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News & Views |
Flying with ionic wind
Aeroplanes use propellers and turbines, and are typically powered by fossil-fuel combustion. An alternative method of propelling planes has been demonstrated that does not require moving parts or combustion.
- Franck Plouraboué
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Letter |
Flight of an aeroplane with solid-state propulsion
A solid-state propulsion system can sustain powered flight, as demonstrated by an electroaerodynamically propelled heavier-than-air aeroplane.
- Haofeng Xu
- , Yiou He
- & Steven R. H. Barrett
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Books & Arts |
Ethics at the cutting edge, beastly movers and shakers, and teeth as time machines: Books in brief.
Barbara Kiser reviews five of the week’s best science picks.
- Barbara Kiser
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News |
Dandelion seeds fly using ‘impossible’ method never before seen in nature
The seeds contain a lot of open space, which seems to be the key to sustaining flight.
- Jeremy Rehm
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Research Highlight |
Water waves grow tall with help from a trick of light
Ring-shaped invention channels waves to triple their height — a potential boon to wave energy.
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Research Highlight |
How to achieve levitation with an ordinary piece of laboratory kit
Castor oil allows for stable magnetic levitation of a laboratory ‘flea’.
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Research Highlight |
How to get droplets just right
A formula can predict the size of droplets formed by a nozzle’s spray.
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News & Views |
Eighty years of superfluidity
In 1938, two studies demonstrated that liquid helium-4 flows without friction or viscosity at temperatures close to absolute zero. The finding led to major advances in our understanding of low-temperature physics.
- William P. Halperin
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News & Views |
Twenty years of drying droplets
When a particle-laden droplet evaporates on a solid surface, the particles form a ring-like deposit. The explanation for this phenomenon, provided in 1997, has led to advances in many areas of science and engineering.
- Ronald G. Larson
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Books & Arts |
Physics: A classical toolkit
Malcolm Longair extols a long-heralded tome by Roger Blandford and 2017 Nobel laureate Kip Thorne.
- Malcolm Longair
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Letter |
Global Λ hyperon polarization in nuclear collisions
The measurement of an alignment between the angular momentum of a non-central collision between heavy ions and the spin of emitted particles reveals that the fluid produced in the collision is extremely vortical.
- L. Adamczyk
- , J. K. Adkins
- & M. Zyzak
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Letter |
Phytoplankton can actively diversify their migration strategy in response to turbulent cues
Here, marine phytoplankton are shown to diversify their migratory strategy in response to turbulent cues through a rapid change in shape, thus challenging a fundamental paradigm in oceanography that phytoplankton are passively at the mercy of ocean turbulence.
- Anupam Sengupta
- , Francesco Carrara
- & Roman Stocker
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Letter |
Weak synchronization and large-scale collective oscillation in dense bacterial suspensions
Cells in dense bacterial suspensions can self-organize into highly robust collective oscillatory motion, while individual cells move in an erratic manner; their interaction is modelled to reveal a weak synchronization mechanism.
- Chong Chen
- , Song Liu
- & Yilin Wu
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News & Views |
Water flows out of touch
Superhydrophobic surfaces reduce the frictional drag between water and solid materials, but this effect is often temporary. The realization of sustained drag reduction has applications for water vehicles and pipeline flows.
- Björn Hof
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Research Highlights |
Fluid spills from strange straws
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Letter |
Magnetic reversals from planetary dynamo waves
Polarity reversals caused by dynamo waves are demonstrated in a magnetohydrodynamic model that is relevant to planetary cores, suggesting a possible mechanism of geomagnetic reversals.
- Andrey Sheyko
- , Christopher C. Finlay
- & Andrew Jackson
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Research Highlights |
Soft surfaces suppress splash
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News & Views |
Turbulence in a quantum gas
The discovery of a cascade of sound waves across many wavelengths in an ultracold atomic gas advances our understanding of turbulence in fluids governed by quantum mechanics. See Letter p.72
- Brian P. Anderson
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Letter |
Emergence of a turbulent cascade in a quantum gas
The gradual development of a turbulent cascade in a weakly interacting homogeneous Bose gas is observed on application of a periodic driving force.
- Nir Navon
- , Alexander L. Gaunt
- & Zoran Hadzibabic
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Letter |
Massive radius-dependent flow slippage in carbon nanotubes
The pressure-driven flow rate through individual carbon nanotubes is precisely determined from the hydrodynamics of emerging water jets, revealing unexpectedly large and radius-dependent surface slippage.
- Eleonora Secchi
- , Sophie Marbach
- & Lydéric Bocquet
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Research Highlights |
Chameleons' sticky spit grabs prey
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Research Highlights |
Tiny carbon rods blow off steam
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Research Highlights |
How desert moss drinks from air
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News Feature |
The snot-spattered experiments that show how far sneezes really spread
Mathematician Lydia Bourouiba uses high-speed video to break down the anatomy of sneezes and coughs — and to understand infectious disease.
- Corie Lok
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News |
Role of chaos in deep ocean turned upside down
Reversal could change timeline of heat and carbon storage in the seas.
- Devin Powell
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News Feature |
The physics of life
From flocking birds to swarming molecules, physicists are seeking to understand 'active matter' — and looking for a fundamental theory of the living world.
- Gabriel Popkin
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News & Views |
Turbulence spreads like wildfire
A simple model captures the key features of the transition from smooth to turbulent flow for a fluid in a pipe. The findings pave the way for more-complex models and may have engineering ramifications. See Letter p.550
- Michael D. Graham
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Letter |
The rise of fully turbulent flow
Experiments, asymptotic theory and computer simulations of wall-bounded shear flow uncover a bifurcation scenario that explains the transition from localized turbulent patches to fully turbulent flow.
- Dwight Barkley
- , Baofang Song
- & Björn Hof
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News Explainer |
Developing El Niño could be strongest on record
Event could bring rain to drought-stricken California and dry conditions to Australia.
- Chris Cesare
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Research Highlights |
Many microbes make a superfluid