Physics:Knudsen layer
The Knudsen layer, also known as evaporation layer, is the thin layer of vapor near a liquid or solid. It is named after Denmark physicist Martin Knudsen (1871–1949).
Definition
At the interface of a vapor and a liquid/solid, the gas interaction with the liquid/solid dominates the gas behavior, and the gas is, very locally, not in equilibrium.[1] This region, several mean free path lengths thick, is called the Knudsen layer.[2]
Knudsen layer thickness
The Knudsen layer thickness can be approximated by [math]\displaystyle{ l_c }[/math], given by[3]
[math]\displaystyle{ l_c =\frac{k T_s}{\pi d^2 p_s} }[/math],
where [math]\displaystyle{ k }[/math] is Boltzmann's constant, [math]\displaystyle{ T_s }[/math] is the temperature, [math]\displaystyle{ d }[/math] is the molecular diameter and [math]\displaystyle{ p_s }[/math] is the pressure.
Applications
One of the applications of Knudsen layer is in the coma of comets. It has been used specially in the coma chemistry model (ComChem model).[4]
References
- ↑ Dongari, Nishanth; Zhang, Yonghao; Reese, Jason M. (2008). "The 'Knudsen Layer' Effect on Thermal Transiporation of Rarefied Gases". GASMEMS Report. http://www.gasmems.eu/site/www/fichiers/GASMEMS11_QR_12-11_ESR1.pdf.
- ↑ Aoki, K. (2003). "Knudsen Layer for Gas Mixtures". Journal of Statistical Physics 112 (3/4): 629–655. doi:10.1023/A:1023876025363.
- ↑ Gusarov, A. V.; Smurov, I. (2002). "Gas-dynamic boundary conditions of evaporation and condensation: Numerical analysis of the Knudsen layer". Physics of Fluids 14 (12): 4242. doi:10.1063/1.1516211. Bibcode: 2002PhFl...14.4242G.
- ↑ Huebner, W. F. (1987). "First Polymer in Space Identified in Comet Halley". Science 237 (4815): 628–630. doi:10.1126/science.237.4815.628. PMID 17758563. Bibcode: 1987Sci...237..628H.
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