关键词: 颗粒气体/
微重力/
团簇/
落塔
English Abstract
Experimental study of clustering behaviors in granular gases
Wang Hua1 2,Chen Qiong2,
Wang Wen-Guang2,
Hou Mei-Ying2
1.School of Physics, Beijing Institute of Technology, Beijing 100081, China;
2.Key Laboratory of Soft Matter Physics, Beijing National Laboratory for Condense Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Fund Project:Project supported by the Strategic Priority Research Program-SJ-10 of the Chinese Academy of Sciences (Grant No. XDA04020200), the National Natural Science Foundation of China (Grant Nos. 11274354, 11474326), and the Special Fund for Earthquake Research of China (Grant No. 201208011).Received Date:29 June 2015
Accepted Date:27 September 2015
Published Online:05 January 2016
Abstract:Granular materials are widely spread in nature and in industry. Owing to the inelastic collisions between particles and frictions among particles, granular systems are dissipative in nature. This intrinsic dissipative nature causes local clustering in granular gas systems. This is a unique phenomenon compared with the molecular gases. Understanding and predicting the condition and parameter values when this phenomenon happens will be helpful for us to gain knowledge of the conditions of clustering or pattern formations in non-equilibrium complex systems. The clustering phenomenon in granular gas is analyzed using phase-separation modeling of van der Waals-like molecules. The results from the model are verified by molecular dynamics numerical simulations. However, due to the influence of the gravity, experimental verification is difficult in laboratory. In this work, we perform an experiment in micro-gravity environment provided by the drop tower of National Microgravity Laboratory Chinese Academy of Science. In the experiment we for the first time observe the phase-separation clustering phenomenon. Comparing the observation condition with the model prediction, we are able to indirectly obtain the restitution coefficients of particles used in the experiment. A model calculation for the spinodal regime under experimental conditions is performed for possible particle restitution coefficients, and a comparison with the experimental observation allows us to justify the values of the restitution coefficients. It is found that the coefficient is larger for bigger particles. For d=2.5mm titanium particles, the restitution coefficient is higher than 0.8; for d=1mm titanium particles, the restitution coefficient is about 0.8, and for d=0.5mm titanium particles, the restitution coefficient is between 0.6 and 0.8. This useful result can be essential for comparing experimental observation with the theoretical and the numerical results, and is crucial to the success in the SJ-10 satellite experiments.
Keywords: granular gases/
low-gravity/
cluster/
drop tower
