Trittel Torsten, Puzyrev Dmitry, Harth Kirsten, Stannarius Ralf
Department of Engineering, Brandenburg University of Applied Sciences, Magdeburger Str. 50, Brandenburg an der Havel, 14770, Germany.
MARS, Otto von Guericke University Magdeburg, Universitätsplatz 2, Magdeburg, 39106, Germany.
NPJ Microgravity. 2024 Jul 31;10(1):81. doi: 10.1038/s41526-024-00420-5.
A granular gas composed of monodisperse spherical particles was studied in microgravity experiments in a drop tower. Translations and rotations of the particles were extracted from optical video data. Equipartition is violated, the rotational degrees of freedom were excited only to roughly 2/3 of the translational ones. After stopping the mechanical excitation, we observed granular cooling of the ensemble for a period of three times the Haff time, where the kinetic energy dropped to about 5% of its initial value. The cooling rates of all observable degrees of freedom were comparable, and the ratio of rotational and translational kinetic energies fluctuated around a constant value. The distributions of translational and rotational velocity components showed slight but systematic deviations from Gaussians at the start of cooling.
在落塔的微重力实验中研究了由单分散球形颗粒组成的颗粒气体。从光学视频数据中提取了颗粒的平移和旋转。等能均分被破坏，转动自由度仅被激发到平动自由度的大约2/3。在停止机械激发后，我们观察到系综的颗粒冷却持续了三倍哈夫时间，在此期间动能降至其初始值的约5%。所有可观测自由度的冷却速率相当，转动和平动动能之比围绕一个恒定值波动。在冷却开始时，平动和转动速度分量的分布显示出与高斯分布略有但系统的偏差。
