The motive force to settle gas particles in the Maxwell velocity distribution
Abstract
It seems generally believed that the Maxwell velocity distribution of neutral gas particles in steady state is given by the maximum value of entropy. However, the authors consider that there must be other motive force directly acting on gas particles to settle them in the Maxwell distribution regardless of the relative velocity dependence of collision frequency. As is easily understood, the velocity distribution of gas particles can change only through collisions. In both the FTI analysis and the Monte-Carlo simulation, we obtained the Maxwell distribution only assuming the isotropic scattering in the center of mass frame. That is, the probability of velocity dispersion through a collision conserving the kinetic energy gives irreversible relaxation into the Maxwell distribution. This fact implies that the direct motive force acting on gas particles toward the Maxwell distribution is solely the law of energy conservation in collisions. The transport properties of gas particles are also determined through collisions conserving energies and momenta with given collision frequencies. The quantities of state such as entropy can not be considered directly giving influences on gas particles but are the results of sequential collisions statistically independent to each other. This idea is also supported by mathematics in solving the Boltzmann equation.
- Publication:
-
APS Annual Gaseous Electronics Meeting Abstracts
- Pub Date:
- October 1998
- Bibcode:
- 1998APS..GECEMP704I