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The transport of an infinitely thin, hard rod in a random, dense array of point obstacles is investigated by molecular dynamics simulations. Our model mimics the sterically hindered dynamics in dense needle liquids. The center-of-mass…

Statistical Mechanics · Physics 2008-09-22 Felix Höfling , Erwin Frey , Thomas Franosch

We consider a reaction--diffusion equation in a domain consisting of two bulk regions connected via small channels periodically distributed within a thin layer. The height and the thickness of the channels are of order $\epsilon$, and the…

Analysis of PDEs · Mathematics 2020-07-09 Apratim Bhattacharya , Markus Gahn , Maria Neuss-Radu

We have considered a stationary outflowing envelope from the star accelerated by the radiative force in arbitrary optical depth case. Introduced approximations provide satisfactory description of the behavior of the matter flux with…

Astrophysics · Physics 2007-05-23 G. S. Bisnovatyi-Kogan , A. V. Dorodnitsyn

We propose and study a one-dimensional model which consists of two cross-diffusion systems coupled via a moving interface. The motivation stems from the modelling of complex diffusion processes in the context of the vapor deposition of thin…

Analysis of PDEs · Mathematics 2024-07-23 Clément Cancès , Jean Cauvin-Vila , Claire Chainais-Hillairet , Virginie Ehrlacher

We study a reaction-diffusion model posed on two distinct spatial scales that accounts for diffusion, aggregation, fragmentation, and deposition of populations of colloidal particles within a porous material. In this model, the macroscopic…

Analysis of PDEs · Mathematics 2026-04-14 Christos Nikolopoulos , Michael Eden , Adrian Muntean

In this paper we employ homogenization techniques to provide a rigorous derivation of the Darcy scale model for precipitation and dissolution in porous media proposed in [19]. The starting point is the pore scale model in [12], which is a…

Analysis of PDEs · Mathematics 2014-01-29 Kundan Kumar , Maria Neuss-Radu , Iuliu Sorin Pop

Our aim is to study the limit of the solution of reaction-diffusion porous medium equation with linear drift $\displaystyle\partial_t u -\Delta u^m +\nabla \cdot (u \: V)=g(t,x,u) $, as $m\to\infty.$ We study the problem in bounded domain…

Analysis of PDEs · Mathematics 2023-05-10 Noureddine Igbida

In this paper, we derive an effective model for transport processes in periodically perforated elastic media, taking into account, e.g., cyclic elastic deformations as they occur in lung tissue due to respiratory movement. The underlying…

Analysis of PDEs · Mathematics 2022-06-15 Jonas Knoch , Markus Gahn , Maria Neuss-Radu , Nicolas Neuß

Motivated by a problem in heterogeneous catalysis, we study a model for irreversible first-order reactions in which gas transport occurs only by diffusion, and reaction occurs only at a small number of well-localized sites. The main problem…

Probability · Mathematics 2015-10-06 Renato Feres , Matt Wallace

The problem of the diffusion evolution of a pore filled with molecular hydrogen in a spherical granule in a hydrogen medium is solved. The initial position of the pore is displaced relative to the center of the granule. A nonlinear system…

Mesoscale and Nanoscale Physics · Physics 2022-03-31 M. I. Kopp , P. N. Ostapchuk , V. V. Yanovsky

Uchaikin suggested a mathematical model of an anomalous diffusion in a space was suggested. This model origins in an investigation of processes in complex systems with variable structure: glasses, liquid crystals, biopolymers, proteins and…

Probability · Mathematics 2007-05-23 G. Sh. Tsitsiashvili , A. E. Yashin

The problem of deriving a gradient flow structure for the porous medium equation which is {\em thermodynamic}, in that it arises from the large deviations of some microscopic particle system, is studied. To this end, a rescaled zero-range…

Probability · Mathematics 2025-03-25 Benjamin Gess , Daniel Heydecker

The percolation of a liquid through a porous material is investigated with the help of equations of the Onsager type. An expression is derived for the molecular attraction, starting from Sutherland's potential approximation to the van der…

Other Condensed Matter · Physics 2015-05-13 D. Mostacci , V. Molinari , M. Premuda

We propose a three-component reaction-diffusion system yielding an asymptotic logarithmic time-dependence for a moving interface. This is naturally related to a Stefan-problem for which both one-sided Dirichlet-type and von Neumann-type…

Statistical Mechanics · Physics 2015-05-27 Soghra Safaverdi , Gerard T. Barkema , Eddy Kunnen , Adam M. Urbanowicz , Christian Maes

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

An oxidation process is simulated for a bundle of metal tubes in a cross-flow. A fluid flow is governed by the incompressible Navier-Stokes equations. To describe the transport of oxygen, the corresponding convection-diffusion equation is…

Computational Engineering, Finance, and Science · Computer Science 2017-08-15 Alexander G. Churbanov , Oleg Iliev , Valery F. Strizhov , Petr N. Vabishchevich

We study a system of interacting particles in a periodically moving external potential, within the simplest possible description of paradigmatic symmetric exclusion process on a ring. The model describes diffusion of hardcore particles…

Statistical Mechanics · Physics 2014-04-17 Rakesh Chatterjee , Sakuntala Chatterjee , Punyabrata Pradhan , S. S. Manna

We consider the homogenization of a model of reactive flows through periodic porous media involving a single solute which can be absorbed and desorbed on the pore boundaries. This is a system of two convection-diffusion equations, one in…

Analysis of PDEs · Mathematics 2014-12-30 Grégoire Allaire , Harsha Hutridurga

We use the hyperbolic subdiffusion equation with fractional time derivatives (the generalized Cattaneo equation) to study the transport process of electrolytes in media where subdiffusion occurs. In this model the flux is delayed in a…

Statistical Mechanics · Physics 2009-11-13 Tadeusz Kosztolowicz , Katarzyna D. Lewandowska

We introduce a Darcy-scale model to describe compressible multi-component flow in a fully saturated porous medium. In order to capture cross-diffusive effects between the different species correctly, we make use of the Maxwell--Stefan…

Analysis of PDEs · Mathematics 2020-12-02 Lukas Ostrowski , Christian Rohde