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H?lder estimates for solutions of the Cauchy problem for the porous medium equation with external forces  [PDF]
Masashi Mizuno
Mathematics , 2012, DOI: 10.1007/s00229-012-0572-z
Abstract: We study the interior H\"older regularity problem for weak solutions of the porous medium equation with external forces. Since the porous medium equation is the typical example of degenerate parabolic equations, H\"older regularity is a delicate matter and does not follow by classical methods. Caffrelli-Friedman, and Caffarelli-Vazquez-Wolansky showed H\"older regularity for the model equation without external forces. DiBenedetto and Friedman showed the H\"older continuity of weak solutions with some integrability conditions of the external forces but they did not obtain the quantitative estimates. The quantitative estimates are important for studying the perturbation problem of the porous medium equation. We obtain the scale invariant H\"older estimates for weak solutions of the porous medium equations with the external forces. As a particular case, we recover the well known H\"older estimates for the linear heat equation.
Extinction and Decay Estimates of Solutions for a Class of Porous Medium Equations
Liu Wenjun,Wang Mingxin,Wu Bin
Journal of Inequalities and Applications , 2007,
Abstract: The extinction phenomenon of solutions for the homogeneous Dirichlet boundary value problem of the porous medium equation , is studied. Sufficient conditions about the extinction and decay estimates of solutions are obtained by using -integral model estimate methods and two crucial lemmas on differential inequality.
Gradient estimates for the porous medium equations on Riemannian manifolds  [PDF]
Guangyue Huang,Zhijie Huang,Haizhong Li
Mathematics , 2011,
Abstract: In this paper we study gradient estimates for the positive solutions of the porous medium equation: $$u_t=\Delta u^m$$ where $m>1$, which is a nonlinear version of the heat equation. We derive local gradient estimates of the Li-Yau type for positive solutions of porous medium equations on Riemannian manifolds with Ricci curvature bounded from below. As applications, several parabolic Harnack inequalities are obtained. In particular, our results improve the ones of Lu, Ni, V\'{a}zquez and Villani in [10]. Moreover, our results recover the ones of Davies in [4], Hamilton in [5] and Li and Xu in [7].
Extinction and Decay Estimates of Solutions for a Class of Porous Medium Equations  [cached]
Wenjun Liu,Mingxin Wang,Bin Wu
Journal of Inequalities and Applications , 2007, DOI: 10.1155/2007/87650
Abstract: The extinction phenomenon of solutions for the homogeneous Dirichlet boundary value problem of the porous medium equation ut= ”um+ |u|p ¢ ’1u ¢ ’ 2u, 0 Keywords
Extinction and decay estimates of solutions for a porous medium equation with nonlocal source and strong absorption
Xianghui Xu, Zhong B Fang and Su-Cheol Yi
Boundary Value Problems , 2013, DOI: 10.1186/1687-2770-2013-24
Abstract: In this paper, we investigate extinction properties of the solutions for the initial Dirichlet boundary value problem of a porous medium equation with nonlocal source and strong absorption terms. We obtain some sufficient conditions for the extinction of nonnegative nontrivial weak solutions and the corresponding decay estimates which depend on the initial data, coefficients, and domains.
A new contraction family for porous medium and fast diffusion equation  [PDF]
Ghada Chmaycem,Régis Monneau,Mustapha Jazar
Mathematics , 2014,
Abstract: In this paper, we present a surprising two-dimensional contraction family for porous medium and fast diffusion equations. This approach provides new a priori estimates on the solutions, even for the standard heat equation.
Local Aronson-Bénilan estimates and entropy formulae for porous medium and fast diffusion equations on manifolds  [PDF]
Peng Lu,Lei Ni,Juan-Luis Vázquez,Cédric Villani
Mathematics , 2008,
Abstract: In this work we derive local gradient and Laplacian estimates of the Aronson-B\'enilan and Li-Yau type for positive solutions of porous medium equations posed on Riemannian manifolds with a lower Ricci curvature bound. We also prove similar results for some fast diffusion equations. Inspired by Perelman's work we discover some new entropy formulae for these equations.
Gradient estimates and entropy formulae of porous medium and fast diffusion equations for the Witten Laplacian  [PDF]
Guangyue Huang,Haizhong Li
Mathematics , 2012,
Abstract: We consider gradient estimates to positive solutions of porous medium equations and fast diffusion equations: $$u_t=\Delta_\phi(u^p)$$ associated with the Witten Laplacian on Riemannian manifolds. Under the assumption that the $m$-dimensional Bakry-Emery Ricci curvature is bounded from below, we obtain gradient estimates which generalize the results in [20] and [13]. Moreover, inspired by X. -D. Li's work in [19] we also study the entropy formulae introduced in [20] for porous medium equations and fast diffusion equations associated with the Witten Laplacian. We prove monotonicity theorems for such entropy formulae on compact Riemannian manifolds with non-negative $m$-dimensional Bakry-Emery Ricci curvature
Uniqueness and properties of distributional solutions of nonlocal equations of porous medium type  [PDF]
J?rgen Endal,Espen R. Jakobsen,Félix del Teso
Mathematics , 2015,
Abstract: We study the uniqueness, existence, and properties of bounded distributional solutions of the initial value problem problem for the anomalous diffusion equation $\partial_tu-\mathcal{L}^\mu [\varphi (u)]=0$. Here $\mathcal{L}^\mu$ can be any nonlocal symmetric degenerate elliptic operator including the fractional Laplacian and numerical discretizations of this operator. The function $\varphi:\mathbb{R} \to \mathbb{R}$ is only assumed to be continuous and nondecreasing. The class of equations include nonlocal (generalized) porous medium equations, fast diffusion equations, and Stefan problems. In addition to very general uniqueness and existence results, we obtain $L^1$-contraction and a priori estimates. We also study local limits, continuous dependence, and properties and convergence of a numerical approximation of our equations.
Systems of partial differential equations in porous medium  [PDF]
Tuomo Kuusi,Léonard Monsaingeon,Juha Videman
Mathematics , 2014,
Abstract: We investigate systems of degenerate parabolic equations idealizing reactive solute transport in porous media. Taking advantage of the inherent structure of the system that allows to deduce a scalar Generalized Porous Medium Equation for the sum of the solute concentrations, we show existence of a unique weak solution to the coupled system and derive regularity estimates. We also prove that the system supports solutions propagating with finite speed thus giving rise to free boundaries and interaction of compactly supported initial concentrations of different species.
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