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Surprisingly high probability of evaporation for a molecule passing through the Knudsen layer

E. S. Benilov*

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Phys. Rev. E 111, 044116 – Published 10 April, 2025

DOI: https://doi.org/10.1103/PhysRevE.111.044116

Abstract

The most important characteristics of the Knudsen layer are the temperature jump ΔT between the liquid and vapor and the probability θK that a molecule, emitted by the liquid into the vapor, reaches infinity (as opposed to bouncing back due to collisions). In the present paper, the linearized Bhatnagar-Gross-Krook model is used to calculate ΔT and θK and show that, in the absence of macroscopic gradients of temperature and density, θK≈96.3%. It is then examined how ΔT and θK are affected by a combination of a temperature gradient (heat flux) and the matching density gradient, such that the resulting pressure field is uniform.

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Phys. Rev. E 111, 044116– Published 10 April, 2025
  • Received 10 January 2025
  • Accepted 26 March 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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