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Many theoretical and experimental results show that solute transport in heterogeneous porous media exhibits multi-scaling behaviors. To describe such non-Fickian diffusions, this work provides a distributed order Hausdorff diffusion model…

Fluid Dynamics · Physics 2018-12-05 Yingjie Liang , Wen Chen , Wei Xu , HongGuang Sun

We show how the nonlinear interaction effects `volume filling' and `adhesion' can be incorporated into the fractional subdiffusive transport of cells and individual organisms. To this end, we use microscopic random walk models with…

Statistical Mechanics · Physics 2015-01-20 Peter Straka , Sergei Fedotov

Diffusion-based models have achieved notable empirical successes in reinforcement learning (RL) due to their expressiveness in modeling complex distributions. Despite existing methods being promising, the key challenge of extending existing…

Machine Learning · Computer Science 2024-11-04 Dmitry Shribak , Chen-Xiao Gao , Yitong Li , Chenjun Xiao , Bo Dai

This paper treats the solvability of a semilinear reaction-diffusion system, which incorporates transport (diffusion) and reaction effects emerging from two separated spatial scales: $x$ - macro and $y$ - micro. The system's origin connects…

Analysis of PDEs · Mathematics 2012-02-10 Tasnim Fatima , Adrian Muntean , Toyohiko Aiki

We develop a mathematical model for adsorption based on averaging the flow around, and diffusion inside, adsorbent particles in a column. The model involves three coupled partial differential equations for the contaminant concentration both…

Other Condensed Matter · Physics 2023-11-20 Lucy C. Auton , Maria Aguareles , Abel Valverde , Timothy G. Myers , Marc Calvo-Schwarzwalder

The arrival of molecules in molecular communication via diffusion (MCvD) is a counting process, exhibiting by its nature binomial distribution. Even if the binomial process describes well the arrival of molecules, when considering…

Emerging Technologies · Computer Science 2014-10-29 H. Birkan Yilmaz , Chan-Byoung Chae , Burcu Tepekule , Ali E. Pusane

We consider absorbing chemical reactions in a fluid flow modeled by the coupled advection-reaction-diffusion equations. In these systems, the interplay between chemical diffusion and fluid transportation causes the enhanced dissipation…

Analysis of PDEs · Mathematics 2022-07-27 Siming He , Alexander Kiselev

We investigate a class of aggregation-diffusion equations with strongly singular kernels and weak (fractional) dissipation in the presence of an incompressible flow. Without the flow the equations are supercritical in the sense that the…

Analysis of PDEs · Mathematics 2020-06-09 Katharina Hopf , José L. Rodrigo

In this study, the impact of turbulent diffusion on mixing of biochemical reaction models is explored by implementing and validating different models. An original codebase called CHAD (Coupled Hydrodynamics and Anaerobic Digestion) is…

Computational Engineering, Finance, and Science · Computer Science 2024-03-08 Jeremy Z. Yan , Prashant Kumar , Wolfgang Rauch

The 1D Ising model is the simplest Hamiltonian-based model in statistical mechanics. The sim- plest interacting particle process is the Symmetric Exclusion Process (SEP), a 1D lattice gas of particles that hop symmetrically and cannot…

Statistical Mechanics · Physics 2018-10-11 Joshua D M Hellier , Graeme J Ackland

Stochastic simulation methods can be applied successfully to model exact spatio-temporally resolved reaction-diffusion systems. However, in many cases, these methods can quickly become extremely computationally intensive with increasing…

Quantitative Methods · Quantitative Biology 2016-04-29 Jonathan U. Harrison , Christian A. Yates

Anomalous diffusion, in particular subdiffusion, is frequently invoked as a mechanism of motion in dense biological media, and may have a significant impact on the kinetics of binding/unbinding events at the cellular level. In this work we…

Statistical Mechanics · Physics 2015-06-10 S. B. Yuste , E. Abad , K. Lindenberg

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

A new diffuse interface model for a two-phase flow of two incompressible fluids with different densities is introduced using methods from rational continuum mechanics. The model fulfills local and global dissipation inequalities and is also…

Fluid Dynamics · Physics 2010-11-03 Helmut Abels , Harald Garcke , Günther Grün

We investigate the transport of a single excitation through a chain of weakly coupled subunits. At both ends the chain is exposed to baths which are incorporated by means of a master equation in Lindblad form. This master equation is solved…

Statistical Mechanics · Physics 2009-07-15 Robin Steinigeweg , Marcel Ogiewa , Jochen Gemmer

The mixing effectiveness, i.e., the enhancement of molecular diffusion, of a flow can be quantified in terms of the suppression of concentration variance of a passive scalar sustained by steady sources and sinks. The mixing enhancement…

Fluid Dynamics · Physics 2009-11-13 Takahide Okabe , Bruno Eckhardt , Jean-Luc Thiffeault , Charles R. Doering

We present a dual-resolution molecular dynamics (MD) simulation of liquid water employing a recently introduced Adaptive Resolution Scheme (AdResS). The spatially adaptive molecular resolution procedure allows for changing from a…

Soft Condensed Matter · Physics 2011-11-10 Silvina Matysiak , Cecilia Clementi , Matej Praprotnik , Kurt Kremer , Luigi Delle Site

In diffusion-controlled drug delivery, it is possible for drug molecules to bind to the carrier material and never be released. A common way to incorporate this phenomenon into the governing mechanistic model is to include an irreversible…

Medical Physics · Physics 2024-01-19 Elliot J. Carr

Heterogeneous media diffusion is often described using position-dependent diffusion coefficients and estimated indirectly through mean squared displacement in experiments. This approach may overlook other mechanisms and their interaction…

Statistical Mechanics · Physics 2023-09-11 Haroldo V. Ribeiro , Angel A. Tateishi , Ervin K. Lenzi , Richard L. Magin , Matjaz Perc

Disruption-generated runaway electrons (RE) present an outstanding issue for ITER. The predictive computational studies of RE generation rely on orbit-averaged computations and, as such, they lack the effects from the magnetic field…

Plasma Physics · Physics 2017-01-19 Konsta Särkimäki , Eero Hirvijoki , Joan Decker , Jari Varje , Taina Kurki-Suonio