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.