Energy fluctuations and transitions in non-equilibrium inter-particle collisions
The energy fluctuations and transitions, as well as the random forces, of a Brownian particle in the short-time limit of one single collision are studied using microscopic kinetic theory. Fluctuations and random forces play fundamental roles in non-equilibrium dynamics and statistical mechanics. We...
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| Language: | English |
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Elsevier
2025-07-01
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| Series: | Results in Physics |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2211379725001706 |
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| author | Tongli Wei Xiansheng Cao Yaojin Li Chenglong Jia |
| author_facet | Tongli Wei Xiansheng Cao Yaojin Li Chenglong Jia |
| author_sort | Tongli Wei |
| collection | DOAJ |
| description | The energy fluctuations and transitions, as well as the random forces, of a Brownian particle in the short-time limit of one single collision are studied using microscopic kinetic theory. Fluctuations and random forces play fundamental roles in non-equilibrium dynamics and statistical mechanics. We find that the mean-square of random forces is proportional to the energy fluctuation for Brown particles. By considering collision processes between an incident particle and background molecules within the framework of the hard-sphere collision model, we analytically investigate energy fluctuations and transitions based on microscopic kinetic theories. Results for the example of the thermal equilibrium gas show that the energy fluctuations arise from two distinct contributions: kinetic fluctuations resulting from the random selection of scattering cross-section positions, which are proportional to the particle’s initial energy; and thermal fluctuations associated with the velocity distribution of molecules, which are proportional to gas temperature. We demonstrate that the energy flux density is equal to the temperature difference ΔT multiplied by the thermal conductivity coefficient κ in two mixed gases under thermal equilibrium. Therefore, a microscopic kinetic perspective is provided for the second law of thermodynamics in this specific scenario. Our finding helps understand random dynamics and relaxation processes in non-equilibrium systems. |
| format | Article |
| id | doaj-art-ae8b44bfe9e341e78d75d01f176a590c |
| institution | DOAJ |
| issn | 2211-3797 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Results in Physics |
| spelling | doaj-art-ae8b44bfe9e341e78d75d01f176a590c2025-08-20T03:09:52ZengElsevierResults in Physics2211-37972025-07-017410827610.1016/j.rinp.2025.108276Energy fluctuations and transitions in non-equilibrium inter-particle collisionsTongli Wei0Xiansheng Cao1Yaojin Li2Chenglong Jia3Key Laboratory of Physics and Photoelectric Information Functional Materials Sciences and Technology, Microelectronics and Solid-State Electronics Device Research Center, School of Electrical and Information Engineering, North Minzu University, Yinchuan 750021, China; Corresponding author.School of Microelectronics and Control Engineering, Changzhou University, Changzhou, 213164, ChinaDepartment of Physics, School of Science, Lanzhou University of Technology, Lanzhou 730050, ChinaLanzhou Center for Theoretical Physics & Key Laboratory of Theoretical Physics of Gansu Province, Lanzhou University, Lanzhou 730000, ChinaThe energy fluctuations and transitions, as well as the random forces, of a Brownian particle in the short-time limit of one single collision are studied using microscopic kinetic theory. Fluctuations and random forces play fundamental roles in non-equilibrium dynamics and statistical mechanics. We find that the mean-square of random forces is proportional to the energy fluctuation for Brown particles. By considering collision processes between an incident particle and background molecules within the framework of the hard-sphere collision model, we analytically investigate energy fluctuations and transitions based on microscopic kinetic theories. Results for the example of the thermal equilibrium gas show that the energy fluctuations arise from two distinct contributions: kinetic fluctuations resulting from the random selection of scattering cross-section positions, which are proportional to the particle’s initial energy; and thermal fluctuations associated with the velocity distribution of molecules, which are proportional to gas temperature. We demonstrate that the energy flux density is equal to the temperature difference ΔT multiplied by the thermal conductivity coefficient κ in two mixed gases under thermal equilibrium. Therefore, a microscopic kinetic perspective is provided for the second law of thermodynamics in this specific scenario. Our finding helps understand random dynamics and relaxation processes in non-equilibrium systems.http://www.sciencedirect.com/science/article/pii/S2211379725001706Brownian motionNon-equilibrium statistical mechanicsMicroscopic kinetic theoriesEnergy transitionEnergy fluctuationCollision theories |
| spellingShingle | Tongli Wei Xiansheng Cao Yaojin Li Chenglong Jia Energy fluctuations and transitions in non-equilibrium inter-particle collisions Results in Physics Brownian motion Non-equilibrium statistical mechanics Microscopic kinetic theories Energy transition Energy fluctuation Collision theories |
| title | Energy fluctuations and transitions in non-equilibrium inter-particle collisions |
| title_full | Energy fluctuations and transitions in non-equilibrium inter-particle collisions |
| title_fullStr | Energy fluctuations and transitions in non-equilibrium inter-particle collisions |
| title_full_unstemmed | Energy fluctuations and transitions in non-equilibrium inter-particle collisions |
| title_short | Energy fluctuations and transitions in non-equilibrium inter-particle collisions |
| title_sort | energy fluctuations and transitions in non equilibrium inter particle collisions |
| topic | Brownian motion Non-equilibrium statistical mechanics Microscopic kinetic theories Energy transition Energy fluctuation Collision theories |
| url | http://www.sciencedirect.com/science/article/pii/S2211379725001706 |
| work_keys_str_mv | AT tongliwei energyfluctuationsandtransitionsinnonequilibriuminterparticlecollisions AT xianshengcao energyfluctuationsandtransitionsinnonequilibriuminterparticlecollisions AT yaojinli energyfluctuationsandtransitionsinnonequilibriuminterparticlecollisions AT chenglongjia energyfluctuationsandtransitionsinnonequilibriuminterparticlecollisions |