Whirlpool in a water tank reveals long-predicted wave turbulence

When water drains from a bathtub, a whirlpool often forms above the drain, and its narrow core can start to wobble and twist. For almost 150 years, physicists have predicted that these wobbles can become turbulent, passing energy from large ripples down to ever smaller ones. Until now, however, this "Kelvin-wave turbulence" had never been seen directly in an experiment.

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