The ‘breakup’ of a water stream into droplets is not caused by external noise or dysfunctional nozzles but by “thermal capillary waves,” physicists have found.
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Why is the leaky faucet – that most irksome domestic malaise – so universal? Perhaps its scourge may be behind us now as a new scientific breakthrough seems to have cracked the physics of the incessant drip-drip.
A new paper published in Physical Review Lettershas explained how a water jet breaks up into unstoppable droplets. Researchers from the University of Amsterdam found that the disturbances that trigger the breakup of ‘laminar jets’, i.e. the arc-shaped stream of liquids, into droplets are not caused by external noise or dysfunctional nozzles but by “thermal capillary waves”.
Simply speaking, the team found that even when a jet is isolated from external noise, it will still have heat-driven capillary waves. The source of the heat is random thermal motion in the liquid. These waves act like ‘seed’ disturbances and have an amplitude of about one ångström, or one ten-billionth of a metre. They eventually grow and make the jet break into droplets.
This is no frivolous finding: per the paper, it could have several application in areas involving droplet formation, such as inkjet printing, food technology, aerosol drug delivery, and DNA sampling.
Published – December 05, 2025 09:00 am IST
