Computational study of 3D rarefied gas flow in microchannel with 90 bend

Rovenskaya, O. I.

doi:10.1016/j.euromechflu.2016.04.008

Cited by 11 publications

(22 citation statements)

References 19 publications

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“…The ratio of the total length L to the width of the channel H sets to 13.5 while the solid surfaces of the channel extend to infinity in the direction perpendicular to the x-y plane, so the problem is effectively two-dimensional. 5,[40][41][42] Due to the fact that the material of silicon, which is commonly used for micron-sized devices, is a good heat conductor, the gas flow in the micro-channel could be considered isothermal. 13 In this work, the gas flow is driven by the pressure difference between the inlet/outlet of the channel and we are interested in the influence of bend on the MFR at various Knudsen numbers.…”

Section: Formulation Of the Problemmentioning

confidence: 99%

“…Agrawal et al attributed this slight increment in MFR to the numerical error, 10 while Rovenskaya et al 5 and White et al 12 explained that this is attributed to the increase of the local Knudsen at the inner corner tip, which leads to the increase of the local slip velocity and decrease of the local shear stress.…”

Section: The Enhancement and Reduction Of Mfr At Different Knudsenmentioning

confidence: 99%

“…For instance, micro heat exchanger generally uses a serpentine channel containing many bends to keep the device efficient and compactable. 5 Therefore, the study of gas flows through complex micro-channels has great practical importance. Over the years, systematic understanding of internal rarefied gas flows has attracted attention in both experimental and theoretical 2 research.…”

Section: Introductionmentioning

confidence: 99%

“…As the emergence of bend could lead to some new and counter-intuitive phenomena, e.g., the mass flow rate (MFR) might increase in bent channels 5,[10][11][12] , a detailed investigation on the bending effect in gas flow through micro-channels would be significantly helpful for the design of MEMS.…”

Section: Introductionmentioning

confidence: 99%

“…It has been applied to investigate the MFRs and the pressure distributions in bent channels under different Mach numbers and Reynolds numbers 12,23,24 , where the flow field and the pressure distribution along the bend are found to be similar to those in the straight channel, except for some differences near the corner of the bend. Although White et al 12 attributed such discrepancies to the change of rarefied effect, Rovenskaya 5 showed that the differences are still present with fixed Knudsen number and gradually become significant when the Mach number increases. This indicates that the local influence of the bend is due to the gas compressibility.…”

Section: Introductionmentioning

confidence: 99%

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

Liu

Tang

et al. 2018

Physics of Fluids

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Micro-bends are frequently encountered in micro-electro-mechanical systems (MEMS) as a basic unit of complex geometry. It is essential for a deep understanding of the rarefied gas flow through bent channel. In this paper, a two-dimensional pressure-driven gas flow in a micro-channel with two bends is investigated 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 of MFR is not due to the rarefaction effect but 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.

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