## Differential and Integral Equations

- Differential Integral Equations
- Volume 13, Number 10-12 (2000), 1201-1232.

### Stationary profiles of degenerate problems when a parameter is large

J. García-Melián and J. Sabina de Lis

#### Abstract

The structure of positive solutions to nonlinear diffusion problems of the form $-\text{div}\ (|{\nabla} u|^{p-2}{\nabla} u) = \lambda f(u)$, in $\Omega$, $u = 0$ on $\partial \Omega$, $p > 1$, $\Omega \subset \mathbb R^N$ a bounded, smooth domain, is precisely studied as $\lambda \to +\infty $, for a class of logistic-type nonlinearities $f(u)$. By logistic it is understood that $f(u)/u^{p-1}$ is decreasing in $u > 0$, $f(u) \sim m u^{p-1}$, $m > 0$, as $u\to 0+$, while $f$ has a positive zero $u = u_0$ of order $k$. It is shown that the positive solution ${u_\lambda}$ homogenizes towards $u_0$ as $\lambda \to +\infty $, and develops a boundary layer near $\partial\Omega$ whose width is exactly measured. On the other hand, the arising of ``dead cores" $\{{u_\lambda} = u_0\}$ for $\lambda$ large is shown in the parameters regime $k < p-1$, the distance $\text{dist}(\{{u_\lambda} = u_0\},\partial\Omega)$ to $\partial \Omega$ being also exactly estimated as $\lambda \to +\infty $. Thus, earlier results in [12], [22] are substantially sharpened. In addition, suitable lower-order perturbations at infinity of the problem are studied.

#### Article information

**Source**

Differential Integral Equations Volume 13, Number 10-12 (2000), 1201-1232.

**Dates**

First available in Project Euclid: 21 December 2012

**Permanent link to this document**

https://projecteuclid.org/euclid.die/1356061124

**Mathematical Reviews number (MathSciNet)**

MR1785705

**Zentralblatt MATH identifier**

0976.35021

**Subjects**

Primary: 35J60: Nonlinear elliptic equations

Secondary: 35B15: Almost and pseudo-almost periodic solutions 35B25: Singular perturbations

#### Citation

García-Melián, J.; Sabina de Lis, J. Stationary profiles of degenerate problems when a parameter is large. Differential Integral Equations 13 (2000), no. 10-12, 1201--1232. https://projecteuclid.org/euclid.die/1356061124.