论文标题
淬灭颗粒介质中密度相关性和过量壁力的弹道传播
Ballistic propagation of density correlations and excess wall forces in quenched granular media
论文作者
论文摘要
我们研究了分子动力学计算机模拟中摇动的准二维盒中的颗粒气。在震动振幅突然变化（淬灭）之后，观察到瞬态密度相关性的数量级以外的数量级以外的数量级。相关性的传播是弹道的，与最近研究的布朗颗粒的淬灭相反，布朗颗粒显示出扩散的传播[Rohwer等，Phys。 Rev. Lett。，118，015702（2017），Rohwer等人，物理。 Rev. E，97，032125（2018）]。在足够的液体冷却足够强的情况下，效果通过以不同的缩放行为的均匀冷却状态的聚类来覆盖。我们能够识别不同的淬火制度。在每个制度中，相关性都表现出非常普遍的位置依赖性。在使用侧壁进行的模拟中，我们发现稳态模拟中温度和压力的限制效应，并在改变摇动振幅时会产生额外的瞬态壁压力。瞬态贡献归因于在存在壁的情况下增强流体的松弛。从不兼容的缩放行为中，我们得出的结论是，有和没有侧壁的观察到的效果构成了不同的现象。
We investigate a granular gas in a shaken quasi-two-dimensional box in molecular dynamics computer simulations. After a sudden change (quench) of the shaking amplitude, transient density correlations are observed orders of magnitude beyond the steady-state correlation length scale. Propagation of the correlations is ballistic, in contrast to recently investigated quenches of Brownian particles that show diffusive propagation [Rohwer et al., Phys. Rev. Lett., 118, 015702 (2017), Rohwer et al., Phys. Rev. E, 97, 032125 (2018)]. At sufficiently strong cooling of the fluid the effect is overlaid by clustering instability of the homogeneous cooling state with different scaling behavior. We are able to identify different quench regimes. In each regime correlations exhibit remarkably universal position dependence. In simulations performed with side walls we find confinement effects for temperature and pressure in steady-state simulations, and an additional transient wall pressure contribution upon changing the shaking amplitude. The transient contribution is ascribed to enhanced relaxation of the fluid in the presence of walls. From incompatible scaling behavior we conclude that the observed effects with and without side walls constitute distinct phenomena.
