Projects per year
Abstract
We review some recent developments in the modelling of non-equilibrium (rarefied) gas flows at the micro- and nano-scale, concentrating on two different but promising approaches: extended hydrodynamic models, and lattice Boltzmann methods. Following a brief exposition of the challenges that non-equilibrium poses in micro- and nano-scale gas flows, we turn first to extended hydrodynamics, outlining the effective abandonment of Burnett-type models in favour of high-order regularised moment equations. We show that the latter models, with properly-constituted boundary conditions, can capture critical non-equilibrium flow phenomena quite well. We then review the boundary conditions required if the conventional Navier-Stokes-Fourier (NSF) fluid dynamic model is applied at the micro scale, describing how 2nd-order Maxwell-type conditions can be used to compensate for some of the non-equilibrium flow behaviour near solid surfaces. While extended hydrodynamics is not yet widely-used for real flow problems because of its inherent complexity, we finish this section with an outline of recent 'phenomenological extended hydrodynamics' (PEH) techniques-essentially the NSF equations scaled to incorporate non-equilibrium behaviour close to solid surfaces-which offer promise as engineering models. Understanding non-equilibrium within lattice Boltzmann (LB) framework is not as advanced as in the hydrodynamic framework, although LB can borrow some of the techniques which are being developed in the latter-in particular, the near-wall scaling of certain fluid properties that has proven effective in PEH. We describe how, with this modification, the standard 2nd-order LB method is showing promise in predicting some rarefaction phenomena, indicating that instead of developing higher-order off-lattice LB methods with a large number of discrete velocities, a simplified high-order LB method with near-wall scaling may prove to be just as effective as a simulation tool.
Original language | English |
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Pages (from-to) | 2061-2074 |
Number of pages | 14 |
Journal | Journal of Computational and Theoretical Nanoscience |
Volume | 6 |
Issue number | 10 |
DOIs | |
Publication status | Published - Oct 2009 |
Keywords
- microfluidics
- nanofluidics
- rarefied gas dynamics
- non-equilibrium fluid dynamics
- slip flow
- Knudsen Layer
- micro-scale flows
- nano-scale flows
- extended hydrodynamics
- lattice Boltzmann
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Dive into the research topics of 'Simulating fluid flows in micro and nano devices: the challenge of non-equilibrium behaviour'. Together they form a unique fingerprint.Projects
- 3 Finished
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Novel multi-relaxation time order models for Lattice Bolztman Simulation of Gas Flows
Zhang, Y. (Principal Investigator)
EPSRC (Engineering and Physical Sciences Research Council)
1/03/08 → 28/02/11
Project: Research
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Fluid Flows at the Nano Scale: from Molecular Dynamics to Hydrodynamics
Reese, J. (Principal Investigator) & Scanlon, T. (Co-investigator)
EPSRC (Engineering and Physical Sciences Research Council)
1/10/07 → 30/09/11
Project: Research
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BEYOND NAVIER-STOKES: MEETING THE CHALLENGE OF NON-EQUILIBRIUM GAS DYNAMICS
Reese, J. (Principal Investigator) & McInnes, C. (Co-investigator)
EPSRC (Engineering and Physical Sciences Research Council)
1/10/05 → 31/01/10
Project: Research