Mathematics Colloquium

The Feynman Sprinkler Problem

Speaker: Leif Ristroph, NYU

Location: Warren Weaver Hall 1302

Date: Monday, April 15, 2024, 3:45 p.m.


I'll discuss projects from our Applied Math Lab about a long-standing puzzle in fluid dynamics. The setting is a thought experiment about so-called sprinklers, which are structures that auto-rotate when expelling fluid, and questions of their reversibility or response under suction. The problem has attracted famous physicists such as Mach and Feynman, and there have been many contradictory experiments and passionate disagreements about issues as fundamental as momentum conservation. I'll talk about what our lab experiments show and how math modeling and simulations are helping to make sense of the results. Some of our findings were recently published ( but we have plenty of ongoing work to do.