论文标题
簇增长对冷却颗粒流体中恢复系数的依赖性
Dependence of Cluster Growth on Coefficient of Restitution in a Cooling Granular Fluid
论文作者
论文摘要
从具有均匀空间密度的构型开始，我们在二维无弹性碰撞硬粒子的二维系统中研究动力学，这是一种流行的冷却粒状物质模型。在初始时间段之后，该系统表现出对不均匀状态的交叉，其特征在于富含粒子的簇的形成和生长。我们介绍了簇的平均质量的时间依赖性和通过事件驱动的分子动力学模拟获得的平均动能的时间依赖性，对于恢复系数（$ e $）的广泛值，通过将系统中粒子的总体密度固定到恒定数字中。众所周知，从同质到非均匀政权的交叉发作时间随着人们向弹性极限的发展而强烈增加。然而，我们提出的结果表明，渐近增长独立于$ e $，对于群集的统一定义，其发病与上述交叉的开始不同。换句话说，不仅指数，而且不仅是幂律增长的幅度，而且人们普遍认为是进化的形式，对$ e $的选择非常敏感。尽管很容易将这一事实归因于能量衰减中的类似特征，但我们警告说，我们当前的理解还不够成熟，无法以有意义的方式在群集生长和能量衰减之间建立这种联系。
Starting from configurations having homogeneous spatial density, we study kinetics in a two-dimensional system of inelastically colliding hard particles, a popular model for cooling granular matter. Following an initial time period, the system exhibits a crossover to an inhomogeneous regime that is characterized by the formation and growth of particle-rich clusters. We present results on the time dependence of average mass of the clusters and that of average kinetic energy, obtained via event driven molecular dynamics simulations, for a wide range of values for the coefficient of restitution ($e$), by fixing the overall density of particles in the system to a constant number. The time of onset of crossover from homogeneous to the inhomogeneous regime, as is well known, strongly increases as one moves towards the elastic limit. Nevertheless, our presented results suggest that the asymptotic growth is independent of $e$, for uniform definition of cluster, onset of which has a different $e$-dependence than the onset of above mentioned crossover. In other words, not only the exponent but also the amplitude of the power-law growth, which is widely believed to be the form of the evolution, is at the most very weakly sensitive to the choice of $e$. While it is tempting to attribute this fact to the similar feature in the decay of energy, we caution that our current understanding is not matured enough to draw such a connection between cluster growth and energy decay in a meaningful manner.
