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Related Experiment Video

Updated: Jun 13, 2026

The Diffusion of Passive Tracers in Laminar Shear Flow

The Diffusion of Passive Tracers in Laminar Shear Flow

Published on: May 1, 2018

Diffusion via space discretization method to study the concentration dependence of self-diffusivity under

Marco Sant¹, George K Papadopoulos, Doros N Theodorou

¹School of Chemical Engineering, National Technical University of Athens, 9 Heroon Polytechniou Street, Zografou Campus, Athens 15780, Greece.

The Journal of Chemical Physics

|April 15, 2010

Summary

This summary is machine-generated.

This study introduces a new method to analyze self-diffusivity in periodic media, decomposing the diffusion coefficient to explain concentration-dependent trends in materials like zeolites.

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Area of Science:

Physical Chemistry
Chemical Engineering
Materials Science

Background:

Understanding the concentration dependence of self-diffusivity is crucial for predicting molecular transport in porous materials.
Existing models may not fully capture the complex behaviors observed in heterogeneous systems.

Purpose of the Study:

To develop and validate a novel method for investigating the concentration dependence of self-diffusivity.
To uniquely decompose the self-diffusion coefficient into physically meaningful parameters.
To explain diffusivity trends in periodic media, including zeolites.

Main Methods:

Extension of a second-order Markov process model to periodic media.
Introduction of the minimum-crossing surface concept.
Decomposition of the self-diffusion coefficient into two concentration-dependent parameters.
Application to model systems and the ITQ-1 zeolite for methane and carbon dioxide transport.

Main Results:

A unique decomposition of the self-diffusion coefficient was achieved.
The method successfully explained cases with and without a maximum in self-diffusivity versus concentration.
Analysis of methane and carbon dioxide in ITQ-1 zeolite revealed concentration-dependent diffusivity trends.
The evolution of model parameters correlated with observed diffusivity behavior.

Conclusions:

The novel method provides a robust framework for analyzing concentration-dependent self-diffusivity.
The decomposition offers physical insights into transport mechanisms in periodic media.
The approach elucidates the differing diffusivity behaviors of methane and carbon dioxide in ITQ-1 zeolite.