English

Extinction profile of the logarithmic diffusion equation

Analysis of PDEs 2012-09-26 v4

Abstract

Let uu be the solution of ut=Δloguu_t=\Delta\log u in RN×(0,T)\R^N\times (0,T), N=3 or N5N\ge 5, with initial value u0u_0 satisfying Bk1(x,0)u0Bk2(x,0)B_{k_1}(x,0)\le u_0\le B_{k_2}(x,0) for some constants k1>k2>0k_1>k_2>0 where Bk(x,t)=2(N2)(Tt)+N/(N2)/(k+(Tt)+2/(N2)x2)B_k(x,t) =2(N-2)(T-t)_+^{N/(N-2)}/(k+(T-t)_+^{2/(N-2)}|x|^2) is the Barenblatt solution for the equation. We prove that the rescaled function \4u(x,s)=(Tt)N/(N2)u(x/(Tt)1/(N2),t)\4{u}(x,s)=(T-t)^{-N/(N-2)}u(x/(T-t)^{-1/(N-2)},t), s=log(Tt)s=-\log (T-t), converges uniformly on RN\R^N to the rescaled Barenblatt solution \4Bk0(x)=2(N2)/(k0+x2)\4{B}_{k_0}(x)=2(N-2)/(k_0+|x|^2) for some k0>0k_0>0 as ss\to\infty. We also obtain convergence of the rescaled solution \4u(x,s)\4{u}(x,s) as ss\to\infty when the initial data satisfies 0u0(x)Bk0(x,0)0\le u_0(x)\le B_{k_0}(x,0) in RN\R^N and u0(x)Bk0(x,0)f(x)L1(RN)|u_0(x)-B_{k_0}(x,0)|\le f(|x|)\in L^1(\R^N) for some constant k0>0k_0>0 and some radially symmetric function ff.

Keywords

Cite

@article{arxiv.1012.1915,
  title  = {Extinction profile of the logarithmic diffusion equation},
  author = {Kin Ming Hui and Sunghoon Kim},
  journal= {arXiv preprint arXiv:1012.1915},
  year   = {2012}
}

Comments

The introduction is re-written and some more references are added, 26 pages

R2 v1 2026-06-21T16:55:44.996Z