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We study a fractional diffusion problem in the divergence form in one space dimension. We define a notion of the viscosity solution. We prove existence of viscosity solutions to the fractional diffusion problem with the Dirichlet boundary…

Analysis of PDEs · Mathematics 2019-05-02 Tokinaga Namba , Piotr Rybka

In this paper, we discuss initial-boundary value problems for linear diffusion equation with multiple time-fractional derivatives. By means of the Mittag-Leffler function and the eigenfunction expansion, we reduce the problem to an integral…

Analysis of PDEs · Mathematics 2013-11-12 Zhiyuan Li , Masahiro Yamamoto

In this paper, we study the asymptotic estimate of solution for a mixed-order time-fractional diffusion equation in a bounded domain subject to the homogeneous Dirichlet boundary condition. Firstly, the unique existence and regularity…

Analysis of PDEs · Mathematics 2021-08-26 Zhiyuan Li , Xinchi Huang , Masahiro Yamamoto

The analytical solution of the equation describing diffusion of intrinsic point defects has been obtained for a one-dimensional finite-length domain. This solution is intended for investigating and modeling the changes in defect…

Materials Science · Physics 2014-06-26 O. I. Velichko

This study handles spatial three-dimensional solution of the nonlinear diffusion equation without particular initial conditions. The functional behavior of the equation and the concentration have been studied in new ways. An auxiliary…

General Mathematics · Mathematics 2020-03-16 Henrik Stenlund

Models of diffusive processes that occur on evolving domains are frequently employed to describe biological and physical phenomena, such as diffusion within expanding tissues or substrates. Previous investigations into these models either…

Populations and Evolution · Quantitative Biology 2023-10-09 Stuart T. Johnston , Matthew J. Simpson

This article deals with the initial-boundary value problem for a moderately coupled system of time-fractional diffusion equations. Defining the mild solution, we establish fundamental unique existence, limited smoothing property and…

Analysis of PDEs · Mathematics 2023-03-23 Zhiyuan Li , Xinchi Huang , Yikan Liu

Second initial boundary problem in narrow domains of width $\epsilon\ll 1$ for linear second order differential equations with nonlinear boundary conditions is considered in this paper. Using probabilistic methods we show that the solution…

Probability · Mathematics 2010-11-30 Mark Freidlin , Konstantinos Spiliopoulos

A new solution to the mono-dimensional diffusion equation for time-variable first kind boundary condition is presented where the time-variable function at the surface is derived proposing a surface saturation model. This solution may be…

Materials Science · Physics 2022-12-08 Guglielmo Macrelli

In view of the usefulness and importance of the kinetic equation in certain physical problems, the authors derive the explicit solution of a fractional kinetic equation of general character, that unifies and extends earlier results.…

Classical Analysis and ODEs · Mathematics 2015-05-13 R. K. Saxena , A. M. Mathai , H. J. Haubold

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

We establish the local existence and the uniqueness of solutions of the heat equation with a nonlinear boundary condition for the initial data in uniformly local $L^r$ spaces. Furthermore, we study the sharp lower estimates of the blow-up…

Analysis of PDEs · Mathematics 2014-04-29 Kazuhiro Ishige , Ryuichi Sato

This paper derives physically meaningful boundary conditions for fractional diffusion equations, using a mass balance approach. Numerical solutions are presented, and theoretical properties are reviewed, including well-posedness and steady…

Analysis of PDEs · Mathematics 2017-06-27 Boris Baeumer , Mihály Kovács , Mark M. Meerschaert , Harish Sankaranarayanan

We consider the heat equation with spatially variable thermal conductivity and homogeneous Dirichlet boundary conditions. Using the Method of Fokas or Unified Transform Method, we derive solution representations as the limit of solutions of…

Analysis of PDEs · Mathematics 2022-08-04 Matthew Farkas , Bernard Deconinck

We study whether the solutions of a parabolic equation with diffusion given by the fractional Laplacian and a dominating gradient term satisfy Dirichlet boundary data in the classical sense or in the generalized sense of viscosity…

Analysis of PDEs · Mathematics 2018-05-21 Alexander Quaas , Andrei Rodríguez

We study a nonlocal diffusion operator in a bounded smooth domain prescribing the flux through the boundary. This problem may be seen as a generalization of the usual Neumann problem for the heat equation. First, we prove existence,…

Analysis of PDEs · Mathematics 2007-05-23 C. Cortazar , M. Elgueta , J. D. Rossi , N. Wolanski

Motivated by practical applications in heat conduction and contaminant transport, we consider heat and mass diffusion across a perturbed interface separating two finite regions of distinct diffusivity. Under the assumption of continuity of…

Biological Physics · Physics 2022-01-12 Elliot J. Carr , Dylan J. Oliver , Matthew J. Simpson

We consider a spatially homogeneous advection-diffusion equation in which the diffusion tensor and drift velocity are time-independent, but otherwise general. We derive asymptotic expressions, valid at large distances from a steady point…

Chaotic Dynamics · Physics 2015-05-20 John Grant , Michael Wilkinson

We consider a heat problem with discontinuous diffusion coefficientsand discontinuous transmission boundary conditions with a resistancecoefficient. For all compact $(\epsilon,\delta)$-domains $\Omega\subset\mathbb{R}^n$ with a $d$-set…

Analysis of PDEs · Mathematics 2015-09-08 Claude Bardos , Denis Grebenkov , Anna Rozanova-Pierrat

We establish the fractional diffusion limit of the kinetic scattering equation with diffusive boundary condition in a strongly convex bounded domain $\mathcal{D}\subset\mathbb{R}^d$. According to the nature of the boundary condition, two…

Probability · Mathematics 2025-12-22 Loïc Béthencourt , Nicolas Fournier