Commun. Comput. Phys., 13 (2013), pp. 1330-1356.

Extended Thermodynamic Approach for Non-Equilibrium Gas Flow

G H. Tang 1*, G. X. Zhai 1, W. Q. Tao 1, X. J. Gu 2, D. R. Emerson 2

1 MOE Key Laboratory of Thermo-Fluid Science and Engineering, School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an 710049, P.R. China.
2 Computational Science and Engineering Department, STFC Daresbury Laboratory, Warrington WA4 4AD, UK.

Received 30 October 2011; Accepted (in revised version) 18 May 2012
Available online 8 October 2012


Gases in microfluidic structures or devices are often in a non-equilibrium state. The conventional thermodynamic models for fluids and heat transfer break down and the Navier-Stokes-Fourier equations are no longer accurate or valid. In this paper, the extended thermodynamic approach is employed to study the rarefied gas flow in microstructures, including the heat transfer between a parallel channel and pressure-driven Poiseuille flows through a parallel microchannel and circular microtube. The gas flow characteristics are studied and it is shown that the heat transfer in the non-equilibrium state no longer obeys the Fourier gradient transport law. In addition, the bimodal distribution of streamwise and spanwise velocity and temperature through a long circular microtube is captured for the first time.

AMS subject classifications: 76P05, 82B40

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Key words: Non-equilibrium, moment method, microchannel, friction coefficient.

*Corresponding author.
Email: (G. H. Tang)

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