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arXiv 2102.07807math.APmath-phmath.MP
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集中涡环的全球时间演化

Global time evolution of concentrated vortex rings

Paolo Buttà, Guido Cavallaro, Carlo Marchioro

摘要:

我们研究的时间演化的不可压缩流体的轴对称无旋流,假设初始数据,使初始涡是非常集中的$N$小不相交环的厚度$\varepsilon$和涡量质量的顺序为$|\log\varepsilon|^{ -1}$。当$\varepsilon \to 0$,我们表明,每个涡环的运动收敛到一个简单的平移与恒定的速度(取决于单个环)沿对称轴。我们得到一个尖锐的本地化的涡度支持在径向方向上的时间$t$,而我们只在轴向方向上的浓度属性。这是针对任意(但固定)时间间隔获得的。这项研究是以前的论文arXiv:1904.04785 [math-ph]的完成,其中涡度支持的急剧本地化沿径向和轴向方向,但收敛$\varepsilon\to 0$只工作了很短的时间。

英文摘要:

We study the time evolution of an incompressible fluid with axial symmetry without swirl, assuming initial data such that the initial vorticity is very concentrated inside $N$ small disjoint rings of thickness $\varepsilon$ and vorticity mass of the order of $|\log\varepsilon|^{ -1}$. When $\varepsilon \to 0$ we show that the motion of each vortex ring converges to a simple translation with constant speed (depending on the single ring) along the symmetry axis. We obtain a sharp localization of the vorticity support at time $t$ in the radial direction, whereas we state only a concentration property in the axial direction. This is obtained for arbitrary (but fixed) intervals of time. This study is the completion of a previous paper arXiv:1904.04785 [math-ph], where a sharp localization of the vorticity support was obtained both along the radial and axial directions, but the convergence for $\varepsilon\to 0$ worked only for short times.

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