Complete classification of self-similar solutions for singular polytropic filtration equations

This article concerns the complete classification of self-similar solutions to the singular polytropic filtration equation. We establish the existence and uniqueness of self-similar solutions of the form $u(x,t)=(\beta t)^{-\alpha/\beta}w((\beta t)^{-\frac{1}{\beta}}|x|)$, and the regularity or sing...

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Bibliographic Details
Main Authors: Yanzhi Zheng, Jingxue Yin, Shanming Ji
Format: Article
Language:English
Published: Texas State University 2025-06-01
Series:Electronic Journal of Differential Equations
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Online Access:http://ejde.math.txstate.edu/Volumes/2025/63/abstr.html
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Summary:This article concerns the complete classification of self-similar solutions to the singular polytropic filtration equation. We establish the existence and uniqueness of self-similar solutions of the form $u(x,t)=(\beta t)^{-\alpha/\beta}w((\beta t)^{-\frac{1}{\beta}}|x|)$, and the regularity or singularity at $x=0$, with $\alpha,\beta\in\mathbb{R}$ and $\beta=p-\alpha(1-mp+m)$. The asymptotic behaviors of the solutions near 0 orinfinity are also described. Specifically, when $\beta<0$, there always exist blow up solutions or oscillatory solutions. When $\beta>0$, oscillatory solutions appear if $\alpha>N$, $0<m<1$ and $1<p<2$. The main technical issue for the proof is to overcome the difficulty arising from the doubly nonlinear non-Newtonian polytropic filtration diffusion $\text{div}({|\nabla u^m|}^{p-2} \nabla u^m)$.
ISSN:1072-6691