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In theory, diffusion curves promise complex color gradations for infinite-resolution vector graphics. In practice, existing realizations suffer from poor scaling, discretization artifacts, or insufficient support for rich boundary…

Numerical Analysis · Mathematics 2023-11-27 Seungbae Bang , Kirill Serkh , Oded Stein , Alec Jacobson

In this paper we study the distribution of the temperature within a body where the heat is transported only by radiation. Specifically, we consider the situation where both emission-absorption and scattering processes take place. We study…

Analysis of PDEs · Mathematics 2025-10-01 Elena Demattè , Juan J. L. Velázquez

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

A simple finite element formulation of the outlet gradient boundary condition is presented in the general context of convective-diffusive transport processes. Basically, the method is based on an upstream evaluation of the dependent…

Fluid Dynamics · Physics 2011-11-15 Fabien Cornaton , Pierre Perrochet , Hans-Jörg Diersch

Motivated by a mathematical model for the transport of morphogenes in biological systems, we study existence and uniqueness of entropy solutions for a mixed initial-boundary value problem associated with a nonlinear flux--limited diffusion…

Analysis of PDEs · Mathematics 2012-06-01 Fuensanta Andreu , Juan Calvo , José M. Mazón , Juan Soler

A new definition of conditional invariance for boundary value problems involving a wide range of boundary conditions (including initial value problems as a special case) is proposed. It is shown that other definitions worked out in order to…

Mathematical Physics · Physics 2014-12-23 Roman Cherniha , John R King

A variety of boundary value problems in linear transport theory are expressed as a diffusion equation of the two-way, or forward-backward, type. In such problems boundary data are specified only on part of the boundary, which introduces…

Mathematical Physics · Physics 2019-02-18 Caleb G. Wagner , Richard Beals

This paper is concerned with a class of partial differential equations, which are the linear combinations, with constant coefficients, of the classical flows of the KdV hierarchy. A boundary value problem with inhomogeneous boundary…

Mathematical Physics · Physics 2015-06-18 Mikhail Yu. Ignatyev

We study the well-posedness for initial boundary value problems associated with time fractional diffusion equations with non-homogenous boundary and initial values. We consider both weak and strong solutions for the problems. For weak…

Analysis of PDEs · Mathematics 2020-04-30 Yavar Kian , Masahiro Yamamoto

In this paper, we consider a class of initial-boundary value problems governed by pseudo-parabolic total variation flows. The principal characteristic of our problem lies in the velocity term of the diffusion flux, a feature that can bring…

Analysis of PDEs · Mathematics 2023-09-01 Toyohiko Aiki , Daiki Mizuno , Ken Shirakawa

A singularly perturbed parabolic problem of convection-diffusion type with incompatible inflow boundary and initial conditions is examined. In the case of constant coefficients, a set of singular functions are identified which match certain…

Numerical Analysis · Mathematics 2022-12-20 Jose Luis Gracia , Eugene O'Riordan

Non-local equations of motion contain an infinite number of derivatives and commonly appear in a number of string theory models. We review how these equations can be rewritten in the form of a diffusion-like equation with non-linear…

Astrophysics · Physics 2014-11-18 N. J. Nunes , D. J. Mulryne

We consider nonlinear diffusion equations of the form $\partial_t u= \Delta \phi(u)$ in $\mathbb R^N$ with $N \ge 2.$ When $\phi(s) \equiv s$, this is just the heat equation. Let $\Omega$ be a domain in $\mathbb R^N$, where $\partial\Omega$…

Analysis of PDEs · Mathematics 2011-07-14 Rolando Magnanini , Shigeru Sakaguchi

There has been considerable recent interest in solving non-local equations of motion which contain an infinite number of derivatives. Here, focusing on inflation, we review how the problem can be reformulated as the question of finding…

High Energy Physics - Theory · Physics 2009-02-23 D. J. Mulryne , N. J. Nunes

We consider the numerical integration of Langevin equations for particles in a channel, in the presence of boundary conditions fixing the concentration values at the ends. This kind of boundary condition appears for instance when…

Computational Physics · Physics 2020-07-24 Laureano Ramírez-Piscina

In this paper, we consider initial-boundary value problems for two-component nonlinear systems of time-fractional diffusion equations with the homogeneous Neumann boundary condition and non-negative initial values. The main results are the…

Analysis of PDEs · Mathematics 2024-05-28 Dian Feng , Masahiro Yamamoto

The work presents an integral solution of the time-fractional subdiffusion through a preliminary defined profile with unknown coefficients and the concept of penetration layer well known from the heat diffusion The profile satisfies the…

Mathematical Physics · Physics 2010-12-14 Jordan Hristov

Analytical solutions to heat or diffusion type equations are numerous, but there are rather few explicit solutions for conditions where the thermal conductivity or diffusion tensors are anisotropic. Such solutions have some use in making…

Analysis of PDEs · Mathematics 2015-07-09 Brian D. Wood , Sassan Ostvar

In this paper, we discuss an initial-boundary value problem (IBVP) for the multi-term time-fractional diffusion equation with x-dependent coefficients. By means of the Mittag-Leffler functions and the eigenfunction expansion, we reduce the…

Analysis of PDEs · Mathematics 2018-02-20 Zhiyuan Li , Xinchi Huang , Masahiro Yamamoto

A mixed boundary value problem for the partial differential equation of diffusion in an inhomogeneous medium in a Lipschitz domain is reduced to a system of direct segregated parametrix-based Boundary-Domain Integral Equations (BDIEs). We…

Analysis of PDEs · Mathematics 2020-11-23 S. E. Mikhailov , C. F. Portillo