Dispersion in Porous Media
Dispersion in Porous Media
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DOI：
10.1007/978-94-009-2825-1_8
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
J. Brady;D. Koch
中科院分区：
文献类型：
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作者：
J. Brady;D. Koch
示踪剂在给定介质中的分子扩散率是示踪剂由于其在分子尺度上的速度波动而平均扩散的度量。在宏观尺度上不均匀的介质中，示踪剂在穿过不均匀介质时由于速度的变化会经历额外的扩散。这种由宏观速度波动引起的扩散称为色散，也是本文的主题。在许多自然和人为环境中，热、质量或电势等被动标量在异质介质中的传递是重要的。例如，宏观的非均质性影响电子通过非晶半导体的输运。第二种混相流体或注入表面活性剂的分散可能会限制提高采收率技术的有效性。传热和传质影响整个化学和生化工业中使用的填料床反应器和接触装置的效率和可操作性。河流、地下水和大气中存在复杂的宏观速度场，可大大提高污染物的耗散速度。最后，由于对流和分子扩散在非均质介质中相互竞争而产生的大量分散现象使多孔介质中的分散研究成为一个有趣而令人兴奋的领域。因此，有很多这样的研究。
The molecular diffusivity of a tracer species in a given medium is a measure of the average spread of the tracer due to fluctuations in its velocity on the molecular scale. In a medium that is heterogeneous on a macroscopic scale, a tracer will experience an additional spreading due to variations in its velocity as it moves through the heterogeneous medium. This spreading due to macroscale velocity fluctuations is known as dispersion and is the subject of this article.The transport of passive scalar species such as heat, mass or electric potential in heterogeneous media is important in many natural and man-made settings. For example, macroscopic heterogeneities affect the transport of electrons through amorphous semiconductors. The dispersion of a second miscible fluid or an injected sufactant may limit the effectiveness of enhanced oil recovery techniques. Heat and mass transfer affect the efficiency and operability of packed bed reactors and contacting devices used throughout the chemical and biochemical industry. The rate of dissipation of pollutants may be greatly increased by the complex macroscopic velocity fields present in rivers, ground water flows and the atmosphere. Finally, the large variety of dispersal phenomena made possible by the competition between convection and molecular diffusion in heterogeneous media makes the study of dispersion in porous media an interesting and exciting area. And as a result, there have been many such studies 1-20.