Hybrid continuum-molecular modelling of multiscale internal gas flows

JOURNAL OF COMPUTATIONAL PHYSICS

卷:255

Article

Patronis, Alexander¹  Lockerby, Duncan A.¹  Borg, Matthew K.²  Reese, Jason M.² 

[1] Univ Warwick, Sch Engn, Coventry CV4 7AL, W Midlands, England

[2] Univ Strathclyde, Dept Mech & Aerosp Engn, Glasgow G1 1XJ, Lanark, Scotland

关键词: Multiscale modelling;    Continuum-molecular simulation;    Continuum-particle simulation;    Hybrid methods;    Rarefied gas dynamics;    Micro gas flows;    Compressibility;   

DOI  :  10.1016/j.jcp.2013.08.033

来源: Elsevier

【 摘 要 】

We develop and apply an efficient multiscale method for simulating a large class of low-speed internal rarefied gas flows. The method is an extension of the hybrid atomistic-continuum approach proposed by Borg et al. (2013) [28] for the simulation of micro/nano flows of high-aspect ratio. The major new extensions are: (1) incorporation of fluid compressibility; (2) implementation using the direct simulation Monte Carlo (DSMC) method for dilute rarefied gas flows, and (3) application to a broader range of geometries, including periodic, non-periodic, pressure-driven, gravity-driven and shear-driven internal flows. The multiscale method is applied to micro-scale gas flows through a periodic converging-diverging channel (driven by an external acceleration) and a non-periodic channel with a bend (driven by a pressure difference), as well as the flow between two eccentric cylinders (with the inner rotating relative to the outer). In all these cases there exists a wide variation of Knudsen number within the geometries, as well as substantial compressibility despite the Mach number being very low. For validation purposes, our multiscale simulation results are compared to those obtained from full-scale DSMC simulations: very close agreement is obtained in all cases for all flow variables considered. Our multiscale simulation is an order of magnitude more computationally efficient than the full-scale DSMC for the first and second test cases, and two orders of magnitude more efficient for the third case. (c) 2013 Elsevier Inc. All rights reserved.

【 授权许可】

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