Harth K, Kornek U, Trittel T, Strachauer U, Höme S, Will K, Stannarius R
Institute of Experimental Physics, Otto-von-Guericke Universität Magdeburg, D-39016 Magdeburg, Germany.
Institute of Automation Engineering, Otto-von-Guericke Universität Magdeburg, D-39016 Magdeburg, Germany.
Phys Rev Lett. 2013 Apr 5;110(14):144102. doi: 10.1103/PhysRevLett.110.144102. Epub 2013 Apr 2.
Granular gases are convenient model systems to investigate the statistical physics of nonequilibrium systems. In the literature, one finds numerous theoretical predictions, but only few experiments. We study a weakly excited dilute gas of rods, confined in a cuboid container in microgravity during a suborbital rocket flight. With respect to a gas of spherical grains at comparable filling fraction, the mean free path is considerably reduced. This guarantees a dominance of grain-grain collisions over grain-wall collisions. No clustering was observed, unlike in similar experiments with spherical grains. Rod positions and orientations were determined and tracked. Translational and rotational velocity distributions are non-Gaussian. Equipartition of kinetic energy between translations and rotations is violated.
颗粒气体是研究非平衡系统统计物理学的便捷模型系统。在文献中，人们发现了众多理论预测，但实验却很少。我们研究了一种在亚轨道火箭飞行期间微重力环境下，被限制在长方体容器中的弱激发棒状稀薄气体。与具有可比填充率的球形颗粒气体相比，平均自由程显著减小。这保证了颗粒间碰撞比颗粒与壁面碰撞占主导地位。与类似的球形颗粒实验不同，未观察到聚集现象。确定并跟踪了棒的位置和方向。平动和转动速度分布是非高斯的。平动和转动之间的动能均分被打破。
