Velocity gradient singularity and structure of the velocity profile in the Knudsen layer according to the Boltzmann equation
- Creators
- Lilley, Charles R.
-
Sader, John E.
Abstract
Rarefied gas flow modeling presents significant challenges in the characterization of nanoscale devices and their applications. An important feature of such flows is the Knudsen layer, which is known to exhibit non-Newtonian viscosity behavior. Significantly, recent research has suggested that the effective viscosity at the surface is about half the standard dynamic viscosity. We examine these claims using numerical solutions of the linearized Boltzmann equation and direct simulation Monte Carlo calculations and discover that (i) the flow exhibits a striking power-law dependence on distance from the solid surface and (ii) the velocity gradient is singular at this surface. This finding contradicts these recent claims and has direct implications for gas flow modeling and the design of nanoscale devices.
Copyright and License
© 2007 American Physical Society.
Acknowledgement
The authors thank the referees for their valuable suggestions and gratefully acknowledge the support of the Particulate Fluids Processing Centre, a special research center of the Australian Research Council, and the Australian Research Council Grants Scheme.
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Additional details
- ISSN
- 1550-2376
- Australian Research Council