Abstract
The mean free path (mfp) of molecules increases when the gas pressure is reduced, and at low enough pressure the (mfp) is so large that the molecules begin to bounce from wall to wall of the flow channel rather than collide with each other. When this happens the character of the flow changes. Thus, different flow regimes are encountered depending on the value of the ratio
where Kn is called the Knudsen number. These flow regimes are as follows:
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
References and Further Readings
A.S.D. Barrett, B.D. Power, in Chemical Engineering Practice, ed. by H.W. Cremer, T. Davies, vol. 5 (Academic, New York, 1958)
S. Dushman, Scientific Foundation of Vacuum Technique (Wiley, New York, 1949). Complete and comprehensive
M. Knudsen, Ann. Phys. 28, 75, 999 (1909). These papers laid the foundations and developed the basics of the whole field
R. Loevinger, in Vacuum Equipment and Technique, ed. by A. Guthrie, R.K. Wakerling (McGraw-Hill, New York, 1949). A nice, simple treatment of pumping systems
Author information
Authors and Affiliations
Rights and permissions
Copyright information
© 2014 Springer Science+Business Media New York
About this chapter
Cite this chapter
Levenspiel, O. (2014). Molecular Flow. In: Engineering Flow and Heat Exchange. Springer, Boston, MA. https://doi.org/10.1007/978-1-4899-7454-9_4
Download citation
DOI: https://doi.org/10.1007/978-1-4899-7454-9_4
Published:
Publisher Name: Springer, Boston, MA
Print ISBN: 978-1-4899-7453-2
Online ISBN: 978-1-4899-7454-9
eBook Packages: Chemistry and Materials ScienceChemistry and Material Science (R0)