论文标题
使用分子动力学模拟确定的低温温度下，氦气转运性能的不确定性
Uncertainties in the Transport Properties of Helium Gas at Cryogenic Temperatures Determined Using Molecular Dynamics Simulation
论文作者
论文摘要
在这项研究中，使用经典和量子框架计算了在气相中4HE的传输特性，例如4HE的扩散率，粘度和导热率，在气相中的4HE，温度范围为10 K至150 K的状态点，压力范围为0.10 MPa（1 atm）至0.21 MPA。在经典的分子动力学模拟（MDS）中，使用了绿色kubo（GK）方法。由于通量自相关函数中的随机波动，GK方法具有与之相关的固有不确定性。此外，在10 K至40 K的温度范围内，氦气颗粒的量子性质变得突出。执行的经典MDS不包括这些效果，因此在计算结果中引入了不确定性。我们讨论了平均自相关函数以减少统计波动并执行查普曼奶油蛋白润滑理论中的量子散射相位计算以研究量子效应的有效时间方式。此外，这项研究还提供了在10 K至150 K的低温温度极限中提供的传输性能数据，这在文献中几乎没有研究，并且可以应用于复杂系统中。
In this study, the transport properties, such as diffusivity, viscosity, and thermal conductivity, of 4He at the gaseous phase are computed for state points in the temperature range of 10 K to 150 K and pressure range of 0.10 MPa (1 atm) to 0.21 MPa using classical and quantum frameworks. Within the classical molecular dynamics simulation (MDS), the Green-Kubo (GK) approach is used. The GK method has an inherent uncertainty associated with it due to the random fluctuations in the flux autocorrelation functions. Moreover, in the temperature range of 10 K to 40 K, the quantum nature of the helium gas particles becomes prominent. The classical MDS performed does not include these effects and hence introduces uncertainties in the calculated results. We discuss efficient ways of time averaging the autocorrelation function to reduce statistical fluctuations and perform the quantum scattering phase shift calculations within the Chapman-Cowling theory to study the quantum effects. Furthermore, this study also provides the transport properties data in the cryogenic temperature limit of 10 K to 150 K, which is scarcely studied in the literature and can be applied in complex systems.
