Physicists have discovered new ways to understand turbulence in superfluids – exotic liquids that flow without friction – offering insights that could shape future technologies and fundamental physics research.
University of Queensland PhD candidate Maarten Christenhusz said that, unlike ordinary fluids such as water or air, superfluids never slow down once set in motion.
“Imagine stirring a cup of coffee – eventually, the swirling liquid slows down and stops because of friction,” Mr Christenhusz said.
“Now imagine a magical liquid where the swirling never ends – a fluid so smooth it flows forever without resistance – that’s what scientists call a superfluid.
“Superfluids are remarkable because they defy our everyday experience.
“In normal fluids like air or water, turbulence – the chaotic, swirling motion we see in storms, ocean waves, or even behind a moving car – arises because of viscosity, or internal friction.
“But superfluids have no viscosity, strangely though, turbulence still happens, and this mystery has puzzled physicists for decades.”
Yet, despite having no viscosity, they still exhibit turbulence, raising a fundamental question: where does the turbulence-causing drag come from?
The team found that drag in superfluids is what’s known as scale invariant.
“This means the flow is the same whether you place a pea or an elephant in the fluid, as long as the turbulence level is the same,” Mr Christenhusz said.
The discovery highlights the central role of the Reynolds number – a measure of turbulence already used in classical fluid mechanics – as the key factor in both classical and quantum turbulence.
“This simplifies our framework for studying turbulence,” Mr Christenhusz said.
“Instead of tracking many different variables, we can focus on a single number, which makes predicting and modelling turbulence much more straightforward.”
The researchers also uncovered a surprising twist: objects that are considered streamlined in everyday fluids, such as airplane wings, actually generate more turbulence in superfluids.
This unusual behaviour arises from the quantum nature of the flow, where drag is generated by the formation of quantised vortices – tiny whirlpools unique to quantum systems.
Supervisor on the project, UQ’s Associate Professor Tyler Neely, said these findings not only advance fundamental physics, but also open doors for new superfluid technologies.
“Large and complex devices such as rotation sensors and accelerometers could be designed more efficiently using these principles,” Dr Neely said.
“Importantly, because drag laws in superfluids are universal, we can test designs at small scale before building full systems.”
The work combines state-of-the-art computer modelling with experimental research.
At UQ’s Bose–Einstein Condensation laboratory, researchers can create superfluids in the lab, enabling direct tests of the predictions.
“Our next step is to measure these drag effects experimentally,” Dr Neely said.
“By bridging simulations and laboratory experiments, we hope to deepen our understanding of turbulence in one of physics’ most fascinating systems.”
The research is published in Physical Review Letters.
