Comparison between Classical-Gas behaviours and Granular-Gas ones in micro-gravity :
Abstract:
Recent vibration experiments in
micro-gravity have demonstrated that "granular-gas" state exists only
in Knudsen regime, that its excitation is "supersonic" and that the
probability density function of the pressure of the gas scales as (Aw)3/2. This paper pursues the description of the
experimental results. Then, it compares these ones to what can be predicted
from few simple modelling, which are (i) the classical-gas theory and (ii) the
thermodynamics of a single particle in a 1d box. The anomalous scaling of
pressure fluctuations (Aw)3/2 is
explained by the crossover from the regime of a single collision during the
sampling time, which imposes p~ (Aw) at small
speed, to a multiple collision imposing p~ (Aw)² . Air effect
and effect of g-jitter are discussed and quantified. Influence of grain-grain
collisions is described on the distribution of speed.
Pacs # :
5.40 ; 45.70 ; 62.20 ;
83.70.Fn
poudres
& grains 12 (4), 60-82 (2001)