C0

Type: Concept

As of November 2026, C0 has been mentioned in one podcast episode on Institute for Advanced Study (Jan 2026). Discussed in the context of extending the concept of helicity to continuous volume-preserving flows.

In fluid dynamics, helicity is, under appropriate conditions, an invariant of the Euler equations of fluid flow, having a topological interpretation as a measure of linkage and/or knottedness of vortex lines in the flow. This was first proved by Jean-Jacques Moreau in 1961 and Moffatt derived it in 1969 without the knowledge of Moreau's paper. This helicity invariant is an extension of Woltjer's theorem for magnetic helicity.