颗粒气体的团簇行为

Clustering behavior in granular gases

颗粒体系由于粒子间非弹性碰撞和摩擦等内秉的能量耗散特性,由宏观粒子形成的颗粒气体体系经常会有局部凝聚现象,这是颗粒气体体系与分子气体体系的最大区别之一。理解和预测这一现象的发生将有助于人们对远离平衡态体系的复杂现象(如有序结构、斑图和团簇形成)的认知。这种局部凝聚现象可以类比于分子气体中亚稳分解形成的液滴,将气液相分离用于解释和寻求局部凝聚现象的模型得到了分子动力学模拟的校验。但是实验的校验却由于宏观粒子运动受重力作用的影响难以在实验室中实现。实践十号卫星为我们提供了长时稳定微重力条件,使得实验观察成为可能,有望获得团簇形成及颗粒冷却行为等颗粒动力学重要实验结果。

Owing to the inelastic collisions and frictions among particles, granular systems are dissipative in nature. This intrinsic dissipative nature causes clustering in granular gas systems,the condition when this phenomenon happens will be helpful for gaining knowledge of pattern formations in non- equilibrium complex systems. The clustering phenomenon in granular gas can be modeled theoretically using phase-separation of van der Waals-like molecules. The prediction has been verified by molecular dynamics numerical simulations. However, due to the influence of the gravity, experimental verification is difficult in laboratory. SJ- 10 provides us such an opportunity to gather important experimental evidences.