DSMC investigation of rarefied gas flow through diverging micro- and nanochannels

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• 作者：Amin Ebrahimi ; Ehsan Roohi
• 关键词：Divergent micro/nanochannel ; Rarefied gas flow ; DSMC ; Simplified Bernoulli trials ; Knudsen minimum
• 刊名：Microfluidics and Nanofluidics
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：21
• 期：2
• 全文大小：
• 刊物类别：Engineering
• 刊物主题：Engineering Fluid Dynamics; Biomedical Engineering; Analytical Chemistry; Nanotechnology and Microengineering;
• 出版者：Springer Berlin Heidelberg
• ISSN：1613-4990
• 卷排序：21

文摘

Direct simulation Monte Carlo (DSMC) method with simplified Bernoulli trials (SBT) collision scheme has been used to study the rarefied pressure-driven nitrogen flow through diverging micro- and nanochannels. The fluid behaviours flowing between two plates with different divergence angles ranging between 0° and 17° are described at different pressure ratios (1.5 ≤ Π ≤ 2.5) and Knudsen numbers (0.03 ≤ Kn ≤ 12.7). The primary flow field properties, including pressure, velocity, and temperature, are presented for divergent micro- and nanochannels and are compared with those of a micro- and nanochannel with a uniform cross section. The variations of the flow field properties in divergent micro- and nanochannels which are influenced by the area change, the channel pressure ratio, and the rarefication are discussed. The results show no flow separation in divergent micro- and nanochannels for all the range of simulation parameters studied in the present work. It has been found that a divergent channel can carry higher amounts of mass in comparison with an equivalent straight channel geometry. A correlation between the mass flow rate through micro- and nanochannels, the divergence angle, the pressure ratio, and the Knudsen number has been suggested. The present numerical findings prove the occurrence of Knudsen minimum phenomenon in micro- and nanochannels with non-uniform cross sections.