不同横截面通道中的扩散动力学理论

IF 1.6 4区化学 Q4 CHEMISTRY, PHYSICAL

Molecular Physics Pub Date : 2024-07-05 DOI:10.1080/00268976.2024.2378116

J. Brey, M. I. G. D. Soria, P. Maynar

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引用次数: 0

摘要

研究考虑了在横截面变化的通道中沿纵坐标的自扩散问题。起点是具有适当边界条件的二维恩斯科格-波尔兹曼-洛伦兹动力学方程。在横坐标上进行积分，得到近似的一维动力学方程，并保持原方程的相关特性。然后，考虑到平衡纵向密度的不均匀性，通过改进的查普曼-恩斯科格扩展方法，推导出纵向密度时间演化的宏观方程。该输运方程采用现象学菲克斯-雅各布方程的形式，但含有一个有效扩散系数，该系数包含与平衡纵向密度曲线斜率变化相关的修正。

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Kinetic theory of diffusion in a channel of varying cross section

Self-diffusion along the longitudinal coordinate in a channel of varying cross section is considered. The starting point is the two-dimensional Enskog-Boltzmann-Lorentz kinetic equation with appropriated boundary conditions. It is integrated over the transversal coordinate to get an approximated one-dimensional kinetic equation, keeping the relevant properties of the original one. Then, a macroscopic equation for the time evolution of the longitudinal density is derived, by means of a modified Chapman-Enskog expansion method, that takes into account the inhomogeneity of the equilibrium longitudinal density. This transport equation has the form of the phenomenological Ficks-Jacobs equation, but with an effective diffusion coefficient that contains corrections associated to the variation of the slope of the equilibrium longitudinal density profile.

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来源期刊

Molecular Physics 物理-物理：原子、分子和化学物理

CiteScore

3.60

自引率

5.90%

发文量

269

审稿时长

2 months

期刊介绍： Molecular Physics is a well-established international journal publishing original high quality papers in chemical physics and physical chemistry. The journal covers all experimental and theoretical aspects of molecular science, from electronic structure, molecular dynamics, spectroscopy and reaction kinetics to condensed matter, surface science, and statistical mechanics of simple and complex fluids. Contributions include full papers, preliminary communications, research notes and invited topical review articles.