论文标题
自由冷却颗粒气的相对熵。分子动力学研究
Relative entropy of freely cooling granular gases. A molecular dynamics study
论文作者
论文摘要
尽管原始的玻尔兹曼（Boltzmann）的$ h $ theorem适用于弹性碰撞，但仍然缺乏对非弹性情况的严格概括。尽管如此，在文献中已经推测，速度分布函数相对于均匀冷却状态（HCS）的相对熵代表了足够的非平衡熵样函数，用于分离的自由冷却颗粒气体。在这项工作中，我们提出了分子动力学结果，从而加强了这种猜想，并拒绝了麦克斯韦人在HCS上的选择作为参考分布。这些结果是通过简化的理论玩具模型定性预测的。此外，一个类似麦克斯韦的速度速度插入模拟实验突出了由相对熵监测的颗粒气体动力学的微观不可逆性，其中仅出现短暂的``抗激光''短暂性''瞬时碰撞。
Whereas the original Boltzmann's $H$-theorem applies to elastic collisions, its rigorous generalization to the inelastic case is still lacking. Nonetheless, it has been conjectured in the literature that the relative entropy of the velocity distribution function with respect to the homogeneous cooling state (HCS) represents an adequate nonequilibrium entropy-like functional for an isolated freely cooling granular gas. In this work, we present molecular dynamics results reinforcing this conjecture and rejecting the choice of the Maxwellian over the HCS as a reference distribution. These results are qualitatively predicted by a simplified theoretical toy model. Additionally, a Maxwell-demon-like velocity-inversion simulation experiment highlights the microscopic irreversibility of the granular gas dynamics, monitored by the relative entropy, where a short ``anti-kinetic'' transient regime appears for nearly elastic collisions only.
