Nonequilibrium Casimir pressures in liquids under shear
Nonequilibrium Casimir pressures in liquids under shear
复制标题
剪切下液体中的非平衡卡西米尔压力
DOI：
10.1140/epje/i2019-11868-9
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
J. Sengers
中科院分区：
文献类型：
--
作者：
J. M. O. D. Zárate;T. R. Kirkpatrick;J. Sengers
在定常非平衡态中，流体动力学模之间的耦合引起热涨落的长程化，从而引起非平衡Casimir压力。在这里，我们考虑非平衡Casimir压力引起的液体中的速度梯度。具体来说，我们获得了两个水平板之间液层中剪切诱导压力增强幅度的显式表达式，完成并纠正了文献中先前提出的结果。在相反的非平衡Casimir压力引起的温度或浓度梯度，我们发现，在剪切非平衡的贡献，从短期波动不再是微不足道的。此外，值得注意的是，目前可用的计算机模拟的模型流体在剪切观察的影响，从分子相关性在纳米尺度上，具有不同的物理起源，并不探测剪切引起的压力，从耦合的长波长流体动力学模式。更重要的是，我们发现，在实际的实验条件下，剪切引起的压力增强所造成的粘性加热，而不是由热速度波动。因此，等温的计算机模拟对于解释实验剪切引起的压力增强是无关的。图形摘要
AbstractIn stationary nonequilibrium states coupling between hydrodynamic modes causes thermal fluctuations to become long ranged inducing nonequilibrium Casimir pressures. Here we consider nonequilibrium Casimir pressures induced in liquids by a velocity gradient. Specifically, we have obtained explicit expressions for the magnitude of the shear-induced pressure enhancements in a liquid layer between two horizontal plates that complete and correct results previously presented in the literature. In contrast to nonequilibrium Casimir pressures induced by a temperature or concentration gradient, we find that in shear nonequilibrium contributions from short-range fluctuations are no longer negligible. In addition, it is noted that currently available computer simulations of model fluids in shear observe effects from molecular correlations at nanoscales that have a different physical origin and do not probe shear-induced pressures resulting from coupling of long-wavelength hydrodynamic modes. Even more importantly, we find that in actual experimental conditions, shear-induced pressure enhancements are caused by viscous heating and not by thermal velocity fluctuations. Hence, isothermal computer simulations are irrelevant for the interpretation of experimental shear-induced pressure enhancements.Graphical abstract