The Temperature and Bulk Flow Speed of a Gas Effusing or Evaporating from a Surface into a Void after Reestablishment of Collisional Equilibrium
✍ Scribed by W.F. Huebner; W.J. Markiewicz
- Publisher
- Elsevier Science
- Year
- 2000
- Tongue
- English
- Weight
- 47 KB
- Volume
- 148
- Category
- Article
- ISSN
- 0019-1035
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✦ Synopsis
Molecules effusing, evaporating, or sublimating from a surface into a void are initially not in equilibrium and therefore do not obey the Maxwell velocity distribution function. Starting with a Maxwell transmission distribution of speeds, we calculate from conservation of momentum and energy the temperature and centerof-mass speed of a drifting Maxwell distribution after equilibrium has been reestablished by collisions in the limit of negligible return flux. The drift (bulk flow) speed corresponds to a Mach number larger than 1. As opposed to effusion, vaporization and sublimation are two-phase processes that restrict the pressure and thus the molecular flux, but without influencing the temperature or bulk flow speed.