Picture of DNA strand

Pioneering chemical biology & medicinal chemistry through Open Access research...

Strathprints makes available scholarly Open Access content by researchers in the Department of Pure & Applied Chemistry, based within the Faculty of Science.

Research here spans a wide range of topics from analytical chemistry to materials science, and from biological chemistry to theoretical chemistry. The specific work in chemical biology and medicinal chemistry, as an example, encompasses pioneering techniques in synthesis, bioinformatics, nucleic acid chemistry, amino acid chemistry, heterocyclic chemistry, biophysical chemistry and NMR spectroscopy.

Explore the Open Access research of the Department of Pure & Applied Chemistry. Or explore all of Strathclyde's Open Access research...

Rarefaction throttling effect : Influence of the bend in micro-channel gaseous flow

Liu, Wei and Tang, Guihua and Su, Wei and Wu, Lei and Zhang, Yonghao (2018) Rarefaction throttling effect : Influence of the bend in micro-channel gaseous flow. Physics of Fluids, 30 (8). ISSN 1070-6631

Text (Liu-etal-POF-2018-Rarefaction-throttling-effect-influence-of-the-bend)
Accepted Author Manuscript

Download (1MB)| Preview


    Micro-bends are frequently encountered in micro-electro-mechanical systems as a basic unit of com- plex geometry. It is essential for a deep understanding of the rarefied gas flow through bent channels. In this paper, a two-dimensional pressure-driven gas flow in a micro-channel with two bends is inves- tigated by solving the Bhatnagar-Gross-Krook kinetic equation via the discrete velocity method in the slip and transition flow regimes. The results show that the mass flow rate (MFR) through the bent channel is slightly higher than that in the straight channel in the slip flow regime but drops significantly as the Knudsen number increases further. It is demonstrated that the increase in MFR is not due to the rarefaction effect but due to the increase in cross section of the bent corners. As the rarefaction effect becomes more prominent, the low-velocity zones at the corners expand and the gas flow is “squeezed” into the inner corner. The narrowed flow section is similar to the throttling effect caused by the valve, and both the changes in MFRs and the pressure distribution also confirm this effect. The classical Knudsen minimum changes due to this “rarefaction throttling effect.” The Knudsen number at which the minimum MFR occurs gradually increases with the bend angle and finally disappears in the transition flow regime. In addition, the onset of rarefaction throttling effect shifts to a smaller Knudsen number with a lower tangential momentum accommodation coefficient.