The Onsager conjecture in 2D: a Newton-Nash iteration

Abstract

For any ${\hat{I}}^3<1/3$, we construct a nontrivial weak solution $u$ to the two-dimensional, incompressible Euler equations, which has compact support in time and satisfies $u\in C^3({\mathbb{R}}_t\times {\mathbb{T}}_x^2)$. In particular, the constructed solution does not conserve energy and, thus, settles the flexible part of the Onsager conjecture in two dimensions. The proof involves combining the Nash iteration technique with a new linear Newton iteration.

Exposition extended and title modified slightly. Final journal version