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It is shown that the problem of moisture propagation in porous media with a nonlinear relation between the mass flux and the pressure gradient as a counterpart of the Darcy law exhibits the property of bounded speed of propagation even in…

Analysis of PDEs · Mathematics 2025-05-27 Chiara Gavioli , Pavel Krejčí

The adsorption of particles diffusing in a half-space bounded by the substrate and irreversibly sticking to the substrate upon contacts is investigated. We show that when absorbing particles are planar disks diffusing in the…

Statistical Mechanics · Physics 2018-07-25 P. L. Krapivsky

We study the influence of the boundary conditions at the solid liquid interface on diffusion in a confined fluid. Using an hydrodynamic approach, we compute numerical estimates for the diffusion of a particle confined between two planes.…

Materials Science · Physics 2015-06-25 Anthony Saugey , Laurent Joly , Christophe Ybert , Jean-Louis Barrat , Lyderic Bocquet

We consider the effective surface motion of a particle that freely diffuses in the bulk and intermittently binds to that surface. From an exact approach we derive various regimes of the effective surface motion characterized by physical…

Statistical Mechanics · Physics 2015-05-13 Aleksei V. Chechkin , Irwin M. Zaid , Michael A. Lomholt , Igor M. Sokolov , Ralf Metzler

Motion of particles in many systems exhibits a mixture between periods of random diffusive like events and ballistic like motion. In many cases, such systems exhibit strong anomalous diffusion, where low order moments $< |x(t)|^q >$ with…

Statistical Mechanics · Physics 2015-06-22 Adi Rebenshtok , Sergey Denisov , Peter Hanggi , Eli Barkai

Consider a particle diffusing in a confined volume which is divided into two equal regions. In one region the diffusion coefficient is twice the value of the diffusion coefficient in the other region. Will the particle spend equal…

Dynamical Systems · Mathematics 2015-06-04 P. F. Tupper , Xin Yang

We consider a possibly degenerate porous media type equation over all of $\R^d$ with $d = 1$, with monotone discontinuous coefficients with linear growth and prove a probabilistic representation of its solution in terms of an associated…

Probability · Mathematics 2014-06-30 Viorel Barbu , Michael Roeckner , Francesco Russo

In the present work, the behavior of vacancy pore inside of spherical particle is investigated. On the assumption of quasistationarity of diffusion fluxes, the nonlinear equation set was obtained analytically, that describes completely pore…

Mesoscale and Nanoscale Physics · Physics 2018-09-19 V. V. Yanovsky , M. I. Kopp , M. A. Ratner

Light diffusion is usually associated with thick, opaque media. Indeed, multiple scattering is necessary for the onset of the diffusive regime and such condition is generally not met in almost transparent media. Nonetheless, at long enough…

We study the Brownian motion of a classical particle in one-dimensional inhomogeneous environments where the transition probabilities follow quasiperiodic or aperiodic distributions. Exploiting an exact correspondence with the…

Statistical Mechanics · Physics 2009-10-31 F. Igloi , L. Turban , H. Rieger

The asymptotics of a singularly perturbed problem is constructed. describing the transport of a polydisperse impurity in the atmosphere, taking into account the processes of precipitation and wind pick-up, as well as the processes of…

Analysis of PDEs · Mathematics 2024-12-30 A. V. Nesterov

Diffusion is a fundamental phenomenon that occurs ubiquitously in nature and remains the subject of continuous research interest. Understanding diffusion is a key to understanding leaving systems. In this Chapter, I discuss diffusion of…

Soft Condensed Matter · Physics 2018-10-15 Svyatoslav Kondrat

Deterministic diffusion in temporally oscillating convection is studied for particles with finite mass. The particles are assumed to obey a simple dissipative dynamical system and the particle diffusion is induced by the strange attractor.…

Chaotic Dynamics · Physics 2009-11-07 Hidetsugu Sakaguchi

In this paper we investigate deterministic diffusion in systems which are spatially extended in certain directions but are restricted in size and open in other directions, consequently particles can escape. We introduce besides the…

chao-dyn · Physics 2016-08-31 Z. Kaufmann , H. Lustfeld , A. Nemeth , P. Szepfalusy

The dynamics of thin, non-circular droplets evaporating in the diffusion-limited regime are examined. The challenging non-rectilinear mixed-boundary problem this poses is solved using a novel asymptotic approach and an asymptotic expansion…

Fluid Dynamics · Physics 2023-05-03 Alexander W. Wray , Matthew R. Moore

Two-scale homogenization limits of parabolic cross-diffusion systems in a heterogeneous medium with no-flux boundary conditions are proved. The heterogeneity of the medium is reflected in the diffusion coefficients or by the perforated…

Analysis of PDEs · Mathematics 2018-10-18 Ansgar Juengel , Mariya Ptashnyk

This paper is concerned with a diffusion-controlled moving-boundary problem in drug dissolution, in which the moving front passes from one medium to another for which the diffusion coefficient is many orders of magnitude smaller. It has…

Fluid Dynamics · Physics 2018-04-24 Michael Vynnycky , Sean McKee , Martin Meere , Chris McCormick , Sean McGinty

Epidemic spreading often occurs in spatially heterogeneous environments, yet how quenched heterogeneity reshapes its onset and critical dynamics remains poorly understood. The diffusive epidemic process, a minimal reaction-diffusion model…

Statistical Mechanics · Physics 2026-03-24 Valentin Anfray , Hong-Yan Shih

Densely packed systems of thermal particles in curved geometries are frequently encountered in biological and microfluidic systems. In 2D systems, at sufficiently high surface coverage, diffusive motion is widely known to be strongly…

Statistical Mechanics · Physics 2014-07-22 Remy Kusters , Stefan Paquay , Cornelis Storm

Diffusion is the macroscopic manifestation of disordered molecular motion. Mathematically, diffusion equations are partial differential equations describing the fluid-like large-scale dynamics of parcels of molecules. Spatially…

Fluid Dynamics · Physics 2018-10-26 F. Sattin , A. Bonato , L. Salasnich