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2018 Sharp global estimates for local and nonlocal porous medium-type equations in bounded domains
Matteo Bonforte, Alessio Figalli, Juan Luis Vázquez
Anal. PDE 11(4): 945-982 (2018). DOI: 10.2140/apde.2018.11.945

Abstract

We provide a quantitative study of nonnegative solutions to nonlinear diffusion equations of porous medium-type of the form t u + u m = 0 , m > 1 , where the operator belongs to a general class of linear operators, and the equation is posed in a bounded domain Ω N . As possible operators we include the three most common definitions of the fractional Laplacian in a bounded domain with zero Dirichlet conditions, and also a number of other nonlocal versions. In particular, can be a fractional power of a uniformly elliptic operator with C 1 coefficients. Since the nonlinearity is given by u m with m > 1 , the equation is degenerate parabolic.

The basic well-posedness theory for this class of equations was recently developed by Bonforte and Vázquez (2015, 2016). Here we address the regularity theory: decay and positivity, boundary behavior, Harnack inequalities, interior and boundary regularity, and asymptotic behavior. All this is done in a quantitative way, based on sharp a priori estimates. Although our focus is on the fractional models, our results cover also the local case when is a uniformly elliptic operator, and provide new estimates even in this setting.

A surprising aspect discovered in this paper is the possible presence of nonmatching powers for the long-time boundary behavior. More precisely, when = ( Δ ) s is a spectral power of the Dirichlet Laplacian inside a smooth domain, we can prove that

  • when 2 s > 1 1 m , for large times all solutions behave as dist 1 m near the boundary;

  • when 2 s 1 1 m , different solutions may exhibit different boundary behavior.

This unexpected phenomenon is a completely new feature of the nonlocal nonlinear structure of this model, and it is not present in the semilinear elliptic equation u m = u .

Citation

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Matteo Bonforte. Alessio Figalli. Juan Luis Vázquez. "Sharp global estimates for local and nonlocal porous medium-type equations in bounded domains." Anal. PDE 11 (4) 945 - 982, 2018. https://doi.org/10.2140/apde.2018.11.945

Information

Received: 2 February 2017; Revised: 31 July 2017; Accepted: 22 November 2017; Published: 2018
First available in Project Euclid: 1 February 2018

zbMATH: 06830003
MathSciNet: MR3749373
Digital Object Identifier: 10.2140/apde.2018.11.945

Subjects:
Primary: 35B45, 35B65, 35K55, 35K65

Rights: Copyright © 2018 Mathematical Sciences Publishers

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