Quantitative estimates for the Navier-Stokes equations via spatial concentration
报告人：Professor Tobias Barker (DMA, PSL Research University, CNRS, École Normale Supérieure)
时间：2020-11-20 17:30-18:30
地点：ZOOM
Abstract：It remains open as to whether or not the 3D Navier-Stokes equations lose smoothness (`blow-up') in finite time. Starting from Jean Leray, many authors provided increasingly refined necessary conditions for a finite-time blow-up to occur. The majority of these blow-up behaviours are formulated in terms of critical or subcritical quantities, which are notions relating to the scaling symmetry of the Navier-Stokes equations. Very recently, Terence Tao used a new quantitative approach to infer that certain 'slightly supercritical' quantities for the Navier-Stokes equations must become unbounded near a potential blow-up time.
In this talk I'll discuss a new strategy for proving quantitative bounds for the Navier-Stokes equations, as well as applications to behaviours of potentially singular solutions. As a first application, we prove a new potential blow-up rate, which is optimal for a certain class of potential non-zero backward discretely self-similar solutions. As a second application, we quantify an upper bound for the number of singular points for a solution possessing a scale-invariant bound. As a third application, we quantify a conditional qualitative regularity result of Seregin (2012), which says that if the critical L_{3} norm of the velocity field is bounded along a sequence of times tending to time $T$ then no blow-up occurs at time $T$. This talk is based upon joint work with Christophe Prange (CNRS, Cergy Paris Université)
Zoom Information：
https://zoom.com.cn/j/68499475189?pwd=UzZybVBHQTFPWmN0MUNyT0UzNEE3Zz09
Conference ID： 684 9947 5189
Password: 589026
