arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2006.00716math.AP
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能量超临界II的有限时间爆破

New type II Finite time blow-up for the energy supercritical heat equation

Manuel del Pino, Chen-Chih Lai, Monica Musso, Juncheng Wei, Yifu Zhou

摘要:

考虑具有$(n-3)$阶Sobolev指数\begin{equation*} \begin{cases} u_t=Δu+u^{3},~&\mbox{ in } Ω\times (0,T),\\ u(x,t)=u|_{\partialΩ},~&\mbox{ on } \partialΩ\times (0,T),\\ u(x,0)=u_0(x),~&\mbox{ in } Ω, \end{cases} \end{equation*}的能量超临界热方程,其中$5\leq n\leq 7$,$Ω=\R^n$或$Ω\subset \R^n$是具有特殊对称性的光滑有界区域.我们构造了第二类有限时间爆破解$u(x,t)$,其中奇异性沿着$(n-4)$维{ \em收缩球}在$Ω$中发生。更准确地说,在首阶,解$u(x,t)$具有急剧缩放的形式$$u(x,t)\approx \la^{-1}(t)\frac{2\sqrt{2}}{1+\left|\frac{(r,z)-(ξ_r(t),ξ_z(t))}{\la(t)}\right|^2}$$,其中$r=\sqrt{x_1^2+\cdots+x_{n-3}^2}$、$z=(x_{n-2},x_{n-1},x_n)$和$x=(x_1,\cdots,x_n)\inΩ$。此外,还得到了某些固定$z_0$的奇点位置$$(ξ_r(t),ξ_z(t))\sim (\sqrt{2(n-4)(T-t)},z_0)~\mbox{ as }~t\nearrow T,$$和爆破速率$$\la(t)\sim \frac{T-t}{|\log(T-t)|^2}~\mbox{ as }~t\nearrow T.$$。这是抛物情形下的一个全新现象。

英文摘要:

We consider the energy supercritical heat equation with the $(n-3)$-th Sobolev exponent \begin{equation*} \begin{cases} u_t=Δu+u^{3},~&\mbox{ in } Ω\times (0,T),\\ u(x,t)=u|_{\partialΩ},~&\mbox{ on } \partialΩ\times (0,T),\\ u(x,0)=u_0(x),~&\mbox{ in } Ω, \end{cases} \end{equation*} where $5\leq n\leq 7$, $Ω=\R^n$ or $Ω\subset \R^n$ is a smooth, bounded domain enjoying special symmetries. We construct type II finite time blow-up solution $u(x,t)$ with the singularity taking place along an $(n-4)$-dimensional {\em shrinking sphere} in $Ω$. More precisely, at leading order, the solution $u(x,t)$ is of the sharply scaled form $$u(x,t)\approx \la^{-1}(t)\frac{2\sqrt{2}}{1+\left|\frac{(r,z)-(ξ_r(t),ξ_z(t))}{\la(t)}\right|^2}$$ where $r=\sqrt{x_1^2+\cdots+x_{n-3}^2}$, $z=(x_{n-2},x_{n-1},x_n)$ with $x=(x_1,\cdots,x_n)\inΩ$. Moreover, the singularity location $$(ξ_r(t),ξ_z(t))\sim (\sqrt{2(n-4)(T-t)},z_0)~\mbox{ as }~t\nearrow T,$$ for some fixed $z_0$, and the blow-up rate $$\la(t)\sim \frac{T-t}{|\log(T-t)|^2}~\mbox{ as }~t\nearrow T.$$ This is a completely new phenomenon in the parabolic setting.

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