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JOURNALS // Matematicheskii Sbornik // Archive

Mat. Sb., 1995 Volume 186, Number 12, Pages 151–172 (Mi sm96)

This article is cited in 3 papers

Evolution of the support of a solution with unbounded energy of quasi-linear degenerate parabolic equation of arbitrary order

A. E. Shishkov

Institute of Applied Mathematics and Mechanics, Ukraine National Academy of Sciences

Abstract: The Cauchy problem for a quasi-linear degenerate parabolic equation in divergence from with energy space $L_p\bigl(0,T;W_{p,\operatorname{loc}}^m(\mathbb R^n)\bigr)$, $m\geqslant 1$, $p>2$, $n\geqslant 1$ and with initial function $u_0(x)\in L_{2,\operatorname{loc}}(\mathbb R^n)$ is considered. The existence of a generalized solution $u(x,t)$ is proved for $u_0(x)$ growing at infinity at the rate:
$$ \int_{|x|<\tau}u_0(x)^2\,dx<c\tau^{n+\frac{2mp}{p-2}} \qquad \forall\,\tau>\tau'>0, \quad c<\infty. $$
For more sever constraints on the growth of $u_0(x)$ several fairly wide uniqueness classes for the above-mentioned solution are discovered. The question of describing the geometry of the domain $\Omega(t)\equiv\mathbb R^n\setminus\operatorname{supp}_xu(x,t)$ for $\Omega_0\equiv\mathbb R^n\setminus\operatorname{supp}u_0(x)\ne\varnothing$ is considered. In case when the domain $\Omega_0$ is unbounded, estimates in terms of the global properties of the initial function $u_0(x)$ are established that characterize the geometry of $\Omega(t)$ as $t\to\infty$.

UDC: 517.9

MSC: 35K55, 35K65

Received: 03.11.1994


 English version:
Sbornik: Mathematics, 1995, 186:12, 1843–1864

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