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Updated: Apr 27, 2026
08:01
The Diffusion of Passive Tracers in Laminar Shear Flow
Published on: May 1, 2018
9.8K
Crossover from anomalous to normal diffusion in porous media
F D A Aarão Reis1, Dung di Caprio2
1Instituto de Física, Universidade Federal Fluminense, Avenida Litorânea s/n, 24210-340 Niterói RJ, Brazil.
Summary
Random walks in porous materials show anomalous diffusion, transitioning from subdiffusion to normal diffusion. This behavior, influenced by pore structure, explains metal atom transport in deposits.
Area of Science:
- Physics
- Materials Science
- Physical Chemistry
Background:
- Studying particle diffusion in porous media is crucial for understanding transport phenomena.
- Ballistic-type growth models create complex porous structures relevant to various applications.
- Simulating external flux into porous solids requires understanding particle entry and movement.
Purpose of the Study:
- Investigate random walks (RW) of particles within porous deposits.
- Analyze the concentration profiles and diffusion behavior at different depths.
- Explain anomalous diffusion observed in metal atom transport in porous deposits.
Main Methods:
- Simulated random walks of particles entering porous structures.
- Analyzed particle concentration decay as a function of depth (z).
- Developed a model of RW in a tube with decreasing cross-section.
Main Results:
- Observed a crossover from stretched exponential decay to normal diffusion.
- Identified anomalous concentration profiles and subdiffusion in highly porous solids.
- A decreasing cross-section tube model accurately predicted crossover behavior.
Conclusions:
- Anomalous diffusion in porous solids is linked to pore geometry and restricted movement.
- The study provides a framework for interpreting anomalous transport in experimental and computational data.
- Findings may explain observed metal atom diffusion in porous deposits.
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