David H. Freedman in Quanta:
The blob is a cloud of turbulence in a large water tank in the lab of the University of Chicago physicist William Irvine. Unlike every other instance of turbulence that has ever been observed on Earth, Irvine’s blob isn’t a messy patch in a flowing stream of liquid, gas or plasma, or up against a wall. Rather, the blob is self-contained, a roiling, lumpy sphere that leaves the water around it mostly still. To create it and sustain it, Irvine and his graduate student Takumi Matsuzawa must repeatedly shoot “vortex loops” — essentially the water version of smoke rings — at it, eight loops at a time. “We’re building turbulence ring by ring,” said Matsuzawa.
Irvine and Matsuzawa tightly control the loops that are the blob’s building blocks and study the resulting confined turbulence up close and at length. The blob could yield insights into turbulence that physicists have been chasing for two centuries — in a quest that led Richard Feynman to call turbulence the most important unsolved problem in classical physics.