Euler (inviscid) and Navier–Stokes (viscous) equations model continuum fluids. Since Leray (1934), global 3D regularity remains open in the Clay-prize sense.
In the 2020s, advances on blow-up scenarios, near-singular constructions, and assisted verification brought discussion toward conditional results and external forcing.
The pre–September 2026 landscape included both classic analysis programs and large-scale computational experiments.