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In this paper we present a study of anomalous diffusion using a Fokker-Planck description with fractional velocity derivatives. The distribution functions are found using numerical means for varying degree of fractionality observing the…

Plasma Physics · Physics 2014-12-18 Johan Anderson , Eun-jin Kim , Sara Moradi

In this article, we examine the general space-time fractional diffusion equation for left-invariant hypoelliptic homogeneous operators on graded Lie groups. Our study covers important examples such as the time-fractional diffusion equation,…

Analysis of PDEs · Mathematics 2025-01-22 Aparajita Dasgupta , Michael Ruzhansky , Abhilash Tushir

We study nonlinear elliptic equations for operators corresponding to non-stable L\'evy diffusions. We include a sum of fractional Laplacians of different orders. Such operators are infinitesimal generators of non-stable (i.e., non…

Analysis of PDEs · Mathematics 2015-12-16 Xavier Cabre , Joaquim Serra

We study the Cauchy problem for a system of semi-linear coupled fractional-diffusion equations with polynomial nonlinearities posed in $% \mathbb{R}_{+}\times \mathbb{R}^{N}$. Under appropriate conditions on the exponents and the orders of…

Analysis of PDEs · Mathematics 2020-09-22 A. Bashir , A. Alsaedi , M. Berbiche , M Kirane

In this paper, we consider functionals based on moments and non-linear entropies which have a linear growth in time in case of source-type so-lutions to the fast diffusion or porous medium equations, that are also known as Barenblatt…

Analysis of PDEs · Mathematics 2015-01-16 Jean Dolbeault , Giuseppe Toscani

This paper presents different approaches, based on functional inequalities, to study the speed of convergence in total variation distance of ergodic diffusion processes with initial law satisfying a given integrability condition. To this…

Probability · Mathematics 2007-05-23 Patrick Cattiaux , Arnaud Guillin

We present a complete description of the similarity solutions $u_{\alpha}(x,t)=t^{-\alpha/2}f(\Vert x \Vert/\sqrt{t};\alpha)$ for the following nonlinear diffusion equation $$ u_{t}+\gamma\vert u_{t} \vert =\Delta u\qquad(-1<\gamma<1) $$…

Analysis of PDEs · Mathematics 2014-08-26 Rodrigo Meneses Pacheco

We consider an evolution equation involving the fractional powers, of order $s \in (0,1)$, of a symmetric and uniformly elliptic second order operator and Caputo fractional time derivative of order $\gamma \in (1,2]$. Since it has been…

Analysis of PDEs · Mathematics 2019-01-04 Enrique Otarola , Abner J. Salgado

We consider the $d=1$ nonlinear Fokker-Planck-like equation with fractional derivatives $\frac{\partial}{\partial t}P(x,t)=D \frac{\partial^{\gamma}}{\partial x^{\gamma}}[P(x,t) ]^{\nu}$. Exact time-dependent solutions are found for $ \nu =…

Statistical Mechanics · Physics 2009-02-06 Mauro Bologna , Constantino Tsallis , Paolo Grigolini

We consider the Cauchy problem of fractional pseudo-parabolic equation on the whole space $R^n,n\geq 1$. Here, the fractional order $\alpha$ is related to the diffusion-type source term behaving as the usual diffusion term on the high…

Analysis of PDEs · Mathematics 2017-03-28 Lingyu Jin , Lang Li , Shaomei Fang

We consider a class of numerical approximations to the Caputo fractional derivative. Our assumptions permit the use of nonuniform time steps, such as is appropriate for accurately resolving the behavior of a solution whose derivatives are…

Numerical Analysis · Mathematics 2020-12-23 Hong-lin Liao , William McLean , Jiwei Zhang

We propose a unified method for the large space-time scaling limit of \emph{linear} collisional kinetic equations in the whole space. The limit is of \emph{fractional} diffusion type for heavy tail equilibria with slow enough decay, and of…

Analysis of PDEs · Mathematics 2023-02-22 Emeric Bouin , Clément Mouhot

We use the distances introduced in a previous joint paper to exhibit the gradient flow structure of some drift-diffusion equations for a wide class of entropy functionals. Functional inequalities obtained by the comparison of the entropy…

Analysis of PDEs · Mathematics 2012-12-06 Jean Dolbeault , Bruno Nazaret , Giuseppe Savaré

The Caputo time-derivative is usually defined pointwise for well-behaved functions, say, for continuously differentiable functions. Accordingly, in the theory of the partial fractional differential equations with the Caputo derivatives, the…

Analysis of PDEs · Mathematics 2014-11-27 Rudolf Gorenflo , Yuri Luchko , Masahiro Yamamoto

This paper is motivated by the characterization of the optimal symmetry breaking region in Caffarelli-Kohn-Nirenberg inequalities. As a consequence, optimal functions and sharp constants are computed in the symmetry region. The result…

Analysis of PDEs · Mathematics 2016-12-21 Jean Dolbeault , Maria J. Esteban , Michael Loss

We study the regularity of a porous medium equation with nonlocal diffusion effects given by an inverse fractional Laplacian operator. The precise model is $u_t=\nabla\cdot(u\nabla (-\Delta)^{-1/2}u).$ For definiteness, the problem is posed…

Analysis of PDEs · Mathematics 2014-09-30 Luis Caffarelli , Juan Luis Vázquez

In the euclidean space, Sobolev and Hardy-Littlewood-Sobolev inequalities can be related by duality. In this paper, we investigate how to relate these inequalities using the flow of a fast diffusion equation in dimension $d\ge3$. The main…

Analysis of PDEs · Mathematics 2012-06-08 Jean Dolbeault

The carr\'e du champ method is a powerful technique for proving interpolation inequalities with explicit constants in presence of a non-trivial metric on a manifold. The method applies to some classical Gagliardo-Nirenberg-Sobolev…

Analysis of PDEs · Mathematics 2022-02-16 Jean Dolbeault , An Zhang

In this article we investigate the solution of the steady-state fractional diffusion equation on a bounded domain in $\real^{1}$. From an analysis of the underlying model problem, we postulate that the fractional diffusion operator in the…

Numerical Analysis · Mathematics 2016-08-02 V. J. Ervin , N. Heuer , J. P. Roop

We are interested in the time asymptotic location of the level sets of solutions to Fisher-KPP reaction-diffusion equations with fractional diffusion in periodic media. We show that the speed of propagation is exponential in time, with a…

Analysis of PDEs · Mathematics 2012-09-24 Xavier Cabre , Anne-Charline Coulon , Jean-Michel Roquejoffre