Anomalous diffusion in time-fluctuating non-stationary diffusivity landscapes

TL;DR

This paper studies how particles diffuse in complex media with time-changing local diffusivity, analyzing both normal and anomalous diffusion through simulations and analytical methods, considering effects like inertia and confinement.

Contribution

It introduces a model for diffusion with time-fluctuating diffusivity and compares simulation results with analytical solutions across various diffusion regimes.

Findings

Identification of regimes of normal, subdiffusive, and superdiffusive behavior.

Effects of inertia on diffusion dynamics.

Impact of confinement on particle motion.

Abstract

We investigate the ensemble and time averaged mean squared displacements for particle diffusion in a simple model for disordered media by assuming that the local diffusivity is both fluctuating in time and has a deterministic average growth or decay in time. In this study we compare computer simulations of the stochastic Langevin equation for this random diffusion process with analytical results. We explore the regimes of normal Brownian motion as well as anomalous diffusion in the sub- and superdiffusive regimes. We also consider effects of the inertial term on the particle motion. The investigation of the resulting diffusion is performed for unconfined and confined motion.