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arXiv 1505.00528math.AP
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轴对称Navier-斯托克斯方程角速度的临界正则性条件

A critical regularity condition on the angular velocity of axially symmetric Navier-Stokes equations

Qi S. Zhang

摘要:

令$v$为轴对称三维Navier-斯托克斯方程的Leray-Hopf解的速度。证明了当角速度$v_θ$满足一个积分条件时,$v$是正则的.该条件允许满足\[ |v_θ(x, t)| \le \frac{C}{r |\ln r|^{2+ε}}, \quad r<1/2, \]的函数,其中$r$是从$x$到轴的距离,$C$和$ε$是任何正常数。与临界先验界\[ |v_θ(x, t)| \le \frac{C}{r}, \qquad 0< r \le 1/2, \]相比,我们的条件在最坏的情况下偏离了对数因子$|\ln r|^{2+ε}$。这是受到最近有趣的论文\cite{CFZ:1}的启发,其中H. Chen,中国粘蝇D. Y. Fang和T. Zhang建立了关于角速度的几乎临界正则性条件。先前的正则性条件偏离因子$r^{-1}$。证明是基于新的观察,即从不同的角度看,三维轴对称Navier-斯托克斯方程中的所有涡拉伸项都是临界的,而不是通常认为的超临界。

英文摘要:

Let $v$ be the velocity of Leray-Hopf solutions to the axially symmetric three-dimensional Navier-Stokes equations. It is shown that $v$ is regular if the angular velocity $v_θ$ satisfies an integral condition which is critical under the standard scaling. This condition allows functions satisfying \[ |v_θ(x, t)| \le \frac{C}{r |\ln r|^{2+ε}}, \quad r<1/2, \] where $r$ is the distance from $x$ to the axis, $C$ and $ε$ are any positive constants. Comparing with the critical a priori bound \[ |v_θ(x, t)| \le \frac{C}{r}, \qquad 0< r \le 1/2, \]our condition is off by the log factor $|\ln r|^{2+ε}$ at worst. This is inspired by the recent interesting paper \cite{CFZ:1} where H. Chen, D. Y. Fang and T. Zhang establish, among other things, an almost critical regularity condition on the angular velocity. Previous regularity conditions are off by a factor $r^{-1}$. The proof is based on the new observation that, when viewed differently, all the vortex stretching terms in the 3 dimensional axially symmetric Navier-Stokes equations are critical instead of supercritical as commonly believed.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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