#### On the De Gregorio model for 3D Euler equations

Speaker：Prof. Hao Jia（University of Minnesota）

Time：2018.05.25，10:00-12:00

Place：N913

Abstract:

The global regularity problem for 3D Euler equations is an important open problem in PDEs. The main issue is to control vorticity, which could grow due to a stretching term in the equation. The main difficulty is to understand the interplay between the vorticity transportation and vorticity stretching. De Gregorio proposed a one dimensional model, based on a modification of the famous Constantin-Lax-Majda model, to gain insight on this effect. It turns out that this one dimensional model is very interesting. Numerical simulations show global existence, but we do not have a proof. In this talk, we will give a proof of global existence in the perturbative regime near the ground state. The proof reveals some interesting features which are relevant in the large data case as well. It also reveals the distinction between several notions of ``criticality" for some quasilinear equations: critical space for well-posedness, persistence of regularity, and the critical space for global existence and