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arXiv 1811.04410math.AP
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一类快速扩散方程解的消失时间行为

Vanishing time behavior of solutions to the fast diffusion equation

Kin Ming Hui, Soojung Kim

摘要:

设$n\geq 3$、$0< m<\frac{n-2}{n}$和$T>0$。在$\mathbb{R}^n\times(0,T)$中构造了快扩散方程$u_t=Δu^m$的正解,这些正解在时间$T$处为零.通过引入受\cite{DKS}启发的尺度参数$β$,研究了空间无穷远处$β$自相似解的二阶渐近性质.我们还研究了快扩散方程解在$T$消失时刻附近的渐近性态,条件是解的初始值接近于某个自相似解的初始值,并且满足在无穷远处的适当衰减条件.根据参数$β$的范围,我们证明了重新缩放的解决方案收敛到自相似的配置文件或为零的$t\nearrow T$。前者意味着渐近稳定的自相似的解决方案,后者是一个新的消失的现象,即使是$n\ge3$和$m=\frac{n-2}{n+2}\,$的情况下,对应于Yamabe流$\mathbb{R}^n$与度量$g=u^{\frac{4}{n+2}}dx^2$。

英文摘要:

Let $n\geq 3$, $0< m<\frac{n-2}{n}$ and $T>0$. We construct positive solutions to the fast diffusion equation $u_t=Δu^m$ in $\mathbb{R}^n\times(0,T)$, which vanish at time $T$. By introducing a scaling parameter $β$ inspired by \cite{DKS}, we study the second-order asymptotics of the self-similar solutions associated with $β$ at spatial infinity. We also investigate the asymptotic behavior of the solutions to the fast diffusion equation near the vanishing time $T$, provided that the initial value of the solution is close to the initial value of some self-similar solution and satisfies some proper decay condition at infinity. Depending on the range of the parameter $β$, we prove that the rescaled solution converges either to a self-similar profile or to zero as $t\nearrow T$. The former implies asymptotic stabilization towards a self-similar solution, and the latter is a new vanishing phenomenon even for the case $n\ge3$ and $m=\frac{n-2}{n+2}\,$ which corresponds to the Yamabe flow on $\mathbb{R}^n$ with metric $g=u^{\frac{4}{n+2}}dx^2$.

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