三维颗粒气体相分离现象

Phase separation in a three-dimensional granular gas system

颗粒体系是一类复杂的耗散体系.在颗粒气体中,耗散性质会使其内部形成局部的凝聚,类似于真实气体中亚稳分解形成的液滴,因此被认为是颗粒气液两相分离的过程.零重力环境下二维颗粒气体相分离现象已有成熟的流体静力学理论解释,将该理论模型推广到三维情形,发现相分离现象依然存在且具有同样的不稳定性根源,通过理论计算给出了三维相分离发生的具体条件.同时,用分子动力学方法模拟检验了理论结果,并给出了三维颗粒气体相分离的新形貌.

Granular systems,without any energy injection,tend to be clustered or condensed due to inelasticity of the particle collisions.Even in a driven granular gas,this notable phenomenon would be present locally and lead to a spatial inhomogeneity,just like the forming of liquid droplets in gases.The present work,by extending an existing two-dimensional theory,offers a three-dimensional model for such a phase-separation phenomenon in a driven granular gas under zero gravity.According to the model,exact conditions for phase separation are obtained through numerical calculations.Event-driven molecular dynamics simulations confirm the theoretical results,and show new morphologies of phase separation in three-dimensional granular gases.