Global energy identity for 3D weak Navier–Stokes solutions
Establish whether weak (Leray–Hopf) solutions of the three-dimensional incompressible Navier–Stokes equations satisfy the exact global kinetic energy balance with equality (the energy identity), rather than only the global energy inequality, for all positive times and suitable initial data.
References
Whether identity (1.3) holds in three space dimensions remains one of the major open problems for weak solutions of the Navier-Stokes equations.
— A Principle of Maximum Entropy for the Navier-Stokes Equations
(2402.14240 - Chen et al., 22 Feb 2024) in Section 1.1 (equation (1.3))