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arXiv 2102.05286math.AP
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具有径向对称自由边界的高维Fisher-KPP非局部扩散方程

The high dimensional Fisher-KPP nonlocal diffusion equation with free boundary and radial symmetry

Yihong Du, Wenjie Ni

摘要:

研究了具有自由边界的径向对称高维Fisher-KPP非局部扩散方程,揭示了它与最近在\cite{cdjfa}中考虑的一维形式的一些根本区别.从技术上讲,这个高维问题更难处理,因为它涉及两个核函数,这两个核函数以相当隐式的方式从原始核函数$J(|x|)$产生。通过引入新的技术,我们能够确定模型的长时间动态,包括首先找到控制加速传播开始的核函数上的阈值条件,以及确定有限时的传播速度。此外,对于两类重要的核函数,得到了扩展轮廓的精确估计。更确切地说,对于核函数的紧支持,我们表明,对数移位发生从有限波的速度传播,这是显着不同的一维情况下,对于核函数$J(|x|)$表现得像$|x|^{-β}$的$x\in\R^N$接近无穷大,我们得到的速度加速扩展时,$β\in (N, N+1]$,这是确切的范围$β$,其中加速扩展是可能的。这些尖锐的估计是通过构造微妙的上下解,仔细分析所涉及的核函数的基础上获得的。

英文摘要:

We study the radially symmetric high dimensional Fisher-KPP nonlocal diffusion equation with free boundary, and reveal some fundamental differences from its one dimensional version considered in \cite{cdjfa} recently. Technically, this high dimensional problem is much more difficult to treat since it involves two kernel functions which arise from the original kernel function $J(|x|)$ in rather implicit ways. By introducing new techniques, we are able to determine the long-time dynamics of the model, including firstly finding the threshold condition on the kernel function that governs the onset of accelerated spreading, and the determination of the spreading speed when it is finite. Moreover, for two important classes of kernel functions, sharp estimates of the spreading profile are obtained. More precisely, for kernel functions with compact support, we show that logarithmic shifting occurs from the finite wave speed propagation, which is strikingly different from the one dimension case; for kernel functions $J(|x|)$ behaving like $|x|^{-β}$ for $x\in\R^N$ near infinity, we obtain the rate of accelerated spreading when $β\in (N, N+1]$, which is the exact range of $β$ where accelerated spreading is possible. These sharp estimates are obtained by constructing subtle upper and lower solutions, based on careful analysis of the involved kernel functions.

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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