Projects per year
Abstract
The forcedriven Poiseuille flow of dense gases between two parallel plates is investigated through the numerical solution of the generalized Enskog equation for twodimensional hard discs. We focus on the competing effects of the mean free path λ, the channel width L, and the disc diameter σ. For elastic collisions between hard discs, the normalised mass flow rate in the hydrodynamic limit increases with L/σ for a fixed Knudsen number (defined as Kn = λ/L), but is always smaller than that predicted by the Boltzmann equation. Also, for a fixed L/σ, the mass flow rate in the hydrodynamic flow regime is not a monotonically decreasing function of Kn but has a maximum when the solid fraction is about 0.3. Under ultratight confinement the famous Knudsen minimum disappears, and the mass flow rate increases with Kn, and is larger than that predicted by the Boltzmann equation in the freemolecular flow regime; for a fixed Kn, the smaller the L/σ, the larger the mass flow rate. In the transitional flow regime, however, the variation of the mass flow rate with L/σ is not monotonic for a fixed Kn: the minimum mass flow rate occurs at L/σ ≈ 2 ∼ 3. For inelastic collisions, the energy dissipation between the hard discs always enhances the mass flow rate. Anomalous slip velocity is also found, which decreases with increasing Knudsen number. The mechanism for these exotic behaviour is analysed.
Original language  English 

Number of pages  15 
Journal  Journal of Fluid Mechanics 
Early online date  30 Mar 2016 
Publication status  Epub ahead of print  30 Mar 2016 
Keywords
 Poiseuille flow
 dense gases
 nonequilibrium dynamics
 Knusden
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Projects
 3 Finished

PoreScale Study of Gas Flows in Ultratight Porous Media
Zhang, Y. & Scanlon, T.
EPSRC (Engineering and Physical Sciences Research Council)
1/09/15 → 30/09/19
Project: Research

UK Consortium on Mesoscale Engineering Sciences (UKCOMES)
Zhang, Y.
EPSRC (Engineering and Physical Sciences Research Council)
1/06/13 → 31/05/18
Project: Research

NonEquilibrium Fluid Dynamics for Micro/Nano Engineering Systems
Reese, J.
EPSRC (Engineering and Physical Sciences Research Council)
1/01/11 → 16/02/16
Project: Research