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Persistent URL http://purl.org/net/epubs/work/34693
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Record Id 34693
Title Is it safe to use Navier-Stokes for gas microflows?
Abstract Gas phase Micro-Electro-Mechanical-Systems (MEMS) demonstrate that the fluid mechanics at the micron scale can differ significantly from that experienced in the macroscopic world. Effects such as rarefaction and gas-surface interactions need to be taken into account and it is well known that the no-slip boundary condition of the Navier-Stokes equations is no longer valid. Following ideas proposed by Maxwell, it is generally accepted that the Navier-Stokes equations can be extended into the slip-flow regime provided the Knudsen number is less than 0.1. However, improvements in micro-fabrication techniques are enabling systems to be constructed with sub-micron feature dimensions. At this scale, the flow will depart even further from equilibrium conditions and enters the transition flow regime (0.1 < Kn < 10). In practice, a typical MEMS device will have to operate over a range of Knudsen numbers but of particular interest is the range 0.01 < Kn < 1, where it is important to understand whether non-equilibrium effects are significant. The results suggest that for non-planar flows, the error associated with the modified Navier-Stokes equations around Kn = 0.1 may be appreciable. More worryingly, Grad's higher-order Knudsen number approximation also fails to capture the essential physics.
Organisation CCLRC , CSE , CSE-CEG
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Language English (EN)
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Paper In Conference Proceedings In 4th European Congress on computational methods in applied sciences and engineering (ECCOMAS2004), Jyväskylä, Finland, 24-28 Jul 2004, (2004). Bailey_et_al_Eccomas2004.pdf 2004