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Anomalous diffusion phenomena are ubiquitous in complex media, such as biological tissues. A wide class of sub-diffusive phenomena phenomena is described by the time-fractional diffusion equation. The paper investigates the case of…

Classical Analysis and ODEs · Mathematics 2018-10-02 Dimiter Prodanov

In this paper, we consider the inverse scattering problem associated with an inhomogeneous media with a conductive boundary. First, we discuss the inverse conductivity problem of reconstructing the conductivity parameter from scattering…

Analysis of PDEs · Mathematics 2017-12-12 Isaac Harris , Andreas Kleefeld

This paper is devoted to the numerical resolution of an anisotropic non-linear diffusion problem involving a small parameter \varepsilon, defined as the anisotropy strength reciprocal. In this work, the anisotropy is carried by a variable…

Numerical Analysis · Mathematics 2012-10-03 Stéphane Brull , Fabrice Deluzet , Alexandre Mouton

Diffusion problems with anisotropic features arise in the various areas of science and engineering fields. As a Lagrangian mesh-less method, SPH has a special advantage in addressing the diffusion problems due to the the benefit of dealing…

Computational Engineering, Finance, and Science · Computer Science 2024-10-14 Xiaojing Tang , Oskar Haidn , Xiangyu Hu

The paper concerns the discreteness of the eigenvalues and the solvability of the interior transmission problem for anisotropic media. Conditions for the ellipticity of the problem are written explicitly, and it is shown that they do not…

Mathematical Physics · Physics 2012-04-19 Evgeny Lakshtanov , Boris Vainberg

Convection-diffusion equations provide the basis for describing heat and mass transfer phenomena as well as processes of continuum mechanics. To handle flows in porous media, the fundamental issue is to model correctly the convective…

Numerical Analysis · Computer Science 2012-08-29 A. Churbanov , P. Vabishchevich

This paper deals with the numerical study of a nonlinear, strongly anisotropic heat equation. The use of standard schemes in this situation leads to poor results, due to the high anisotropy. An Asymptotic-Preserving method is introduced in…

Numerical Analysis · Mathematics 2012-04-02 Alexei Lozinski , Jacek Narski , Claudia Negulescu

In this paper, we investigate stochastic heat equation with sublinear diffusion coefficients. By assuming certain concavity of the diffusion coefficient, we establish non-trivial moment upper bounds and almost sure spatial asymptotic…

Probability · Mathematics 2023-06-13 Le Chen , Panqiu Xia

Under low-Reynolds-number conditions, dynamics of convection and diffusion are usually considered separately because their dominant spatial and temporal scales are different, but cooperative effects of convection and diffusion can cause…

Fluid Dynamics · Physics 2022-08-04 Yuki Koyano , Hiroyuki Kitahata

This paper develops strong solutions and stochastic solutions for the tempered fractional diffusion equation on bounded domains. First the eigenvalue problem for tempered fractional derivatives is solved. Then a separation of variables, and…

Probability · Mathematics 2016-11-29 Erkan Nane , Mark M. Meerschaert , Palaniappan Vellaisamy

The framework of anisotropic hydrodynamics is used in 3+1 dimensions to analyze behavior of matter produced in ultra-relativistic heavy-ion collisions. The model predictions for the hadronic transverse-momentum spectra, directed and…

Nuclear Theory · Physics 2015-06-05 Wojciech Florkowski , Radoslaw Ryblewski

The atmospheres of planets (including Earth) and the outer layers of stars have often been treated in radiative transfer as plane-parallel media, instead of spherical shells, which can lead to inaccuracy, e.g. limb darkening. We give an…

Statistical Mechanics · Physics 2009-11-11 Michael J. Caola

This paper is devoted to the multigrid convergence analysis for the linear systems arising from the conforming linear finite element discretization of the second order elliptic equations with anisotropic diffusion. The multigrid convergence…

Numerical Analysis · Mathematics 2011-05-09 Guozhu Yu , Jinchao Xu , Ludmil Zikatanov

Nonlinear diffusion equations of spectral transfer are systematically derived for anisotropic magnetohydrodynamics in the regime of wave turbulence. The background of the analysis is the asymptotic Alfv\'en wave turbulence equations from…

Solar and Stellar Astrophysics · Physics 2015-05-19 Sebastien Galtier , Eric Buchlin

We prove the existence of self-similar fundamental solutions (SSF) of the anisotropic porous medium equation in the suitable fast diffusion range. Each of such SSF solutions is uniquely determined by its mass. We also obtain the asymptotic…

Analysis of PDEs · Mathematics 2023-04-25 Filomena Feo , Juan Luis Vázquez , Bruno Volzone

We present a novel artificial diffusion method to circumvent the instabilities associated with the standard finite element approximation of convection-diffusion equations. Motivated by the micromorphic approach, we introduce an auxiliary…

Numerical Analysis · Mathematics 2025-06-19 Soheil Firooz , B. Daya Reddy , Paul Steinmann

When considering fractional diffusion equation as model equation in analyzing anomalous diffusion processes, some important parameters in the model related to orders of the fractional derivatives, are often unknown and difficult to be…

Analysis of PDEs · Mathematics 2019-04-15 Zhiyuan Li , Yikan Liu , Masahiro Yamamoto

Reaction-diffusion equations deliver a versatile tool for the description of reactions in inhomogeneous systems under the assumption that the characteristic reaction scales and the scales of the inhomogeneities in the reactant…

Statistical Mechanics · Physics 2009-11-11 M. G. W. Schmidt , F. Sagues , I. M. Sokolov

We focus on the (sharp) threshold phenomena arising in some reaction-diffusion equations supplemented with some compactly supported initial data. In the so-called ignition and bistable cases, we prove the first sharp quantitative estimate…

Analysis of PDEs · Mathematics 2019-10-10 Matthieu Alfaro , Arnaud Ducrot , Gregory Faye

We study an anisotropic, possibly non-homogeneous version of the evolution $p$-Laplacian equation when fast diffusion holds in all directions. We develop the basic theory and prove symmetrization results from which we derive $L^1$ to…

Analysis of PDEs · Mathematics 2021-05-11 Filomena Feo , Juan Luis Vazquez , Bruno Volzone