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Force-Induced Dispersion in Heterogeneous Media.
1Laboratoire Ondes et Matière d'Aquitaine (LOMA), CNRS, UMR 5798, Université de Bordeaux, F-33400 Talence, France.
Physical Review Letters
|July 25, 2015
Summary
External forces significantly boost Brownian particle dispersion in periodic media. This study shows how electric or gravitational fields can control particle movement and diffusion in heterogeneous materials.
Area of Science:
- Physics
- Physical Chemistry
- Statistical Mechanics
Background:
- Brownian motion describes random particle movement in fluids.
- Diffusivity and mobility govern particle spread in heterogeneous media.
- Periodic media exhibit spatially varying properties.
Purpose of the Study:
- To investigate the impact of external forces on Brownian particle dispersion.
- To analyze how spatially varying diffusivity affects particle movement under external fields.
- To explore the modulation of dispersion in periodic media.
Main Methods:
- Utilizing a Kubo formula for advection-diffusion systems.
- Analyzing particle dispersion in one, two, and three dimensions.
- Simulating the effects of constant applied external forces (e.g., electric, gravitational).
Main Results:
- External forces significantly enhance dispersion along the force direction.
- Perpendicular dispersion is modified, sometimes non-monotonically.
- Spatially varying diffusivity amplifies the effects of external forces.
Conclusions:
- External force fields offer a method to control and enhance particle dispersion.
- This research provides a framework applicable to various periodic advection-diffusion systems.
- The findings open possibilities for manipulating material properties using force fields.
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