Spontaneous Negative Entropy Increments in Granular Flows.
Spontaneous Negative Entropy Increments in Granular Flows.
复制标题
颗粒流中的自发负熵增量。
DOI：
10.1115/1.4049184
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
Ostoja-Starzewski,Martin
中科院分区：
文献类型：
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作者：
Laudani,Rossella;Ostoja-Starzewski,Martin
熵不等式是连续介质力学中的一个公理，在宏观颗粒介质的碰撞动力学过程中，熵不等式被自发破坏。结果福尔斯落在非平衡态热力学涨落定理的范围内，该定理被认为可以取代有限系统的第二定律。这种现象相当于系统随机地显示负熵增量。重点是颗粒介质中的Couette流，由单一尺寸的圆盘（10至104盘的直径为0.01米至1米）与摩擦胡克接触模拟的分子动力学占微极效应。总的来说，它是确定的概率负熵增量减小的欧拉速度梯度的增加，而它往往以S形的方式增加的杨氏模量的磁盘。对于非常广泛的已知材料检查这种行为：从最软的聚合物到最硬的（即，碳炔）。发现圆盘的泊松比对负熵增量发生的概率有微弱的影响。
The entropy inequality, commonly taken as an axiom of continuum mechanics, is found to be spontaneously violated in macroscopic granular media undergoing collisional dynamics. The result falls within the fluctuation theorem of nonequilibrium thermodynamics, which is known to replace the Second Law for finite systems. This phenomenon amounts to the system stochastically displaying negative increments of entropy. The focus is on granular media in Couette flows, consisting of monosized circular disks (with 10 to 104 disks of diameters 0.01 m to 1 m) with frictional-Hookean contacts simulated by molecular dynamics accounting for micropolar effects. Overall, it is determined that the probability of negative entropy increments diminishes with the Eulerian velocity gradient increasing, while it tends to increase in a sigmoidal fashion with the Young modulus of disks increasing. This behavior is examined for a very wide range of known materials: from the softest polymers to the stiffest (i.e., carbyne). The disks’ Poisson ratio is found to have a weak effect on the probability of occurrence of negative entropy increments.